Toole, Floyd E — Sound reproduction- the acoustics and psychoacoustics of loudspeakers and rooms

Yield

861 of 1963 paragraphs kept (43.9%). Target for mining: 30%–50% — on target.

Pre-Assessment

Floyd Toole is a very well-known figure in audio acoustics — he spent decades at the National Research Council of Canada doing controlled loudspeaker listening tests, and later as VP of Acoustic Engineering at Harman International. He is widely regarded as the preeminent practical authority on loudspeaker design and room acoustics, and this book is his definitive synthesis, originally published 2008 with later revisions. Currency is good for a subject that doesn’t move fast; the psychoacoustic models he discusses are built on decades of his and others’ peer-reviewed research, and he’s careful to distinguish evidence from opinion.

This is almost entirely a facts-and-concepts yield. Toole is a scientist, not a speculative writer — expect carefully reasoned, evidence-grounded explanations of how human hearing interacts with loudspeaker dispersion, reflections, and room modes, with practical design/applications throughout. For a mining read aimed at deeper psychoacoustic understanding, the yield profile is high-density concepts and applied models rather than inspiration or speculative frameworks. The main caveat: this is a demanding technical book, so the actionable “nuggets” you extract will require parsing some quantitative content, but the prose is unusually clear for a technical text.

Reading Goal

Prioritizing: Causal Relationships (Understanding how physical stimuli cause perceptual responses is the core of the field.), Factual Claims (Foundational empirical data on hearing is central to psychoacoustics.), Definitional Content (Precise definitions of perceptual terms, thresholds, and model parameters matter here.), Craft and Method (Experimental methods and modeling techniques are key to how psychoacoustic models are built.), Connection Points (Linking models to real applications (audio coding, hearing aids) deepens comprehension.) De-prioritizing: Inspiration and Speculation (Less relevant; the reader wants grounded understanding, not speculative ideas.)

Thesis

Some audible complaints are recording format flaws, not playback faults · ch. 6

Argument

1. Listeners rate neutral, uncolored reproduction as best, preferring it to any coloration. — ch. 6
2. Most listeners can recognize audio excellence when comparing loudspeakers side by side. — ch. 6
3. Anechoic-data equalization differs sharply from room calibration, which is often misused — ch. 6
4. Tube amplifiers audibly color loudspeakers as those become more neutral — ch. 6
5. Loudspeaker design targets are set by human listeners, not engineering metrics — ch. 6
6. Recorded art translation depends on a shared consumer-professional audio standard — ch. 6
7. Human sound-quality judgments are skewed by expectation biases, not just the sound itself. — ch. 6
8. Audio knowledge is best conveyed through discovery history rather than bare facts — ch. 6
9. Neutral reproductions serve as a reliable baseline for tonal preferences — ch. 6
10. Sighted loudspeaker evaluations are contaminated by non-auditory visual and social cues — ch. 7
11. Phase response stops being audible once sound leaves the loudspeaker — ch. 7
12. Randomizing speaker locations is needed to average out room effects. — ch. 7
13. The variety of loudspeaker sounds in the marketplace originates from uncontrolled subjective evaluations — ch. 7
14. Single-stimulus listening relies on capricious long-term memory and yields contradictory opinions — ch. 7
15. Room boundary reflections are the second loudest sounds a listener hears — ch. 7
16. Microphone choice in recordings biases subjective loudspeaker ratings — ch. 7
17. Different loudspeaker topologies each produce characteristic on- and off-axis flaws. — ch. 7
18. Even designer loudspeakers deviate seriously from flat response targets. — ch. 7
19. Early mid-century radios sounded small, colored, and lacking in bass — ch. 7
20. Blind listening shows listeners consistently prefer flat, smooth anechoic frequency response — ch. 7
21. Double-blind evaluation can identify the most transparent loudspeakers — ch. 7
22. Listener judgment reliability declines with age and accumulated noise exposure — ch. 7
23. Early listening tests required repeated short passages heard through every loudspeaker. — ch. 7
24. The knuckle test misjudges cabinets because contact excitation differs from internal pressure. — ch. 7
25. Speaker midrange errors can stem from resonant diaphragm flexure and be fixed by damping. — ch. 7
26. No scientific evidence shows audible break-in changes except minor woofer low-bass compliance — ch. 7
27. Frequency, phase, and impulse responses are mathematically interchangeable descriptions of linear behavior. — ch. 7
28. Smooth flat on- and off-axis response correlates with subjective preference. — ch. 7
29. Signal synthesis enabled creative experimental tests of hearing. — ch. 7
30. Waveform details are relatively unimportant to auditory perception — ch. 7
31. Comparing two sound samples requires accurate auditory memory of a timbral identity. — ch. 7
32. Panel movement alone does not indicate audibly radiated sound. — ch. 7
33. Perceived break-in effects stem from listener adaptation, not product change — ch. 7
34. Room reflections are essential; anechoic listening is deeply unpleasant — ch. 7
35. Blind listeners largely agreed on loudspeaker preferences, matching measurement quality — ch. 7
36. Parametric equalization of minimum-phase resonances also reduces time-domain ringing — ch. 7
37. Instantaneous switching between looped program excerpts yields more revealing audio evaluations. — ch. 7
38. Reflected sound fields cannot be corrected by electronic equalization alone — ch. 7
39. Musicians judge loudspeakers on different rationales and can be inconsistent raters. — ch. 7
40. Audible distortion in quality loudspeakers is rare within intended limits — ch. 7
41. Reliable subjective ratings are prerequisites for validating technical measurements — ch. 7
42. Loudspeaker quality depends on off-axis radiation because rooms reflect it — ch. 7
43. Neutral loudspeakers now exist but are not universally adopted in both domains. — ch. 7
44. Harmonic distortion measurements poorly predict audible annoyance from real music. — ch. 7
45. Non-linear distortion generates new frequencies as level-dependent behavior shifts. — ch. 7
46. British engineering schools restricted colonial students from popular courses even with acceptance letters. — ch. 7
47. Early binaural headphone studies localized sounds inside the head rather than externally. — ch. 7
48. Blind-tested listeners with normal hearing produce reliable, measurement-grade subjective ratings — ch. 7
49. Paired comparisons demand six times more trials than multiple comparisons for four loudspeakers. — ch. 7
50. Equal-level stereo speakers create a phantom image midway between them — ch. 7
51. Early blind loudspeaker comparison relied on single overall preference ratings — ch. 7
52. Silence intervals of half a second to a second aid auditory discrimination accuracy — ch. 7
53. Highly regarded hifi loudspeakers had wildly non-flat anechoic responses — ch. 7
54. Neutral loudspeakers preserve musical inspiration better than colored ones — ch. 7
55. Historical loudspeaker measurements were non-standardized and largely kept from the public — ch. 8
56. Spinorama measurement grew out of loudspeaker-room interaction studies — ch. 8
57. Anechoic chambers lose accuracy below roughly 80 Hz and require correction. — ch. 8
58. Total sound power is a spherical area-weighted sum over full orbitals around a speaker — ch. 8
59. Interpreting mid-tier loudspeaker measurements is harder than spotting extremes — ch. 8
60. Randomizing positions and identifiers cancels room standing-wave biases in double-blind tests — ch. 8
61. Spatially averaged curve families reveal audible resonances hidden in single measurements — ch. 8
62. Room curves are measurement results, not equalization targets, except at bass — ch. 8
63. Audiophile press acclaim and high prices do not reliably predict speakers’ blind-tested performance rankings. — ch. 8
64. Room standing waves dominate below the Schroeder frequency while the loudspeaker controls above it — ch. 8
65. Oblique speaker placement pushes problem reflections into heavily attenuated off-axis angles — ch. 8
66. Listener preferences correlate visually with smooth, flat anechoic on- and off-axis response. — ch. 8
67. Accurate anechoic data plus blind listening tests make psychoacoustic correlations emerge quickly — ch. 8
68. The term spinorama derives from rotating the loudspeaker to gather response data — ch. 8
69. Subjective listening tests require repetition and randomization to be statistically valid — ch. 8
70. Recording monitors with deliberate response errors perpetuate the circle of confusion — ch. 8
71. The LP medium was fundamentally incapable of reproducing master tape sound — ch. 8
72. The distinctive LP sound is an artifact, not fidelity to the master — ch. 8
73. Matched room curves do not guarantee matching direct sound for imaging — ch. 8
74. Low-frequency room resonances dominate how loudspeaker placement affects perceived quality. — ch. 8
75. Bass accounts for roughly 30 percent of perceived sound quality — ch. 8
76. Canadian audio magazines contributed test products and journalists to NRCC blind listening tests — ch. 8
77. Room acoustics were the one loudspeaker variable manufacturers could not control without EQ — ch. 8
78. Professional monitors rated lower than consumer products in blind sound quality tests. — ch. 8
79. Published spinorama measurements frequently violate standard resolution requirements and are then unreliable — ch. 8
80. Record label tape-erasure practices corrupted early CD releases at the source — ch. 8
81. Objective measurements routinely expose flaws that subjective listening reviews miss — ch. 8
82. Digital post-processing enabled low-frequency calibration of anechoic chambers. — ch. 8
83. Untrained listeners reach quick, consistent sound-quality judgments when switching is instantaneous and sequence-blind. — ch. 8
84. Relaxed room-standard requirements eroded the comparability that motivated them — ch. 8
85. Low-Q resonances become audible at peaks below 0.5 dB in the midrange — ch. 8
86. Listener perception depends on sound power, direct sound, and reflections by frequency band — ch. 8
87. Consumers can judge loudspeaker quality from spinorama curves without hearing them — ch. 8
88. Listening window averaging estimates the direct sound heard by a typical audience — ch. 8
89. LP tracing distortion arises because cutter and stylus follow different geometric paths — ch. 8
90. Low-frequency cutoff defined at −10 dB, not −3 dB, best predicts perceived fidelity. — ch. 8
91. Repositioning woofers near the rotation axis improves low-frequency measurement splicing accuracy — ch. 8
92. Single-number loudspeaker ratings mislead because real faults often have straightforward corrections — ch. 8
93. Horizontal and vertical reflections dominate because they are the strongest first reflections. — ch. 8
94. Audibility gaps in loudspeakers stem from inadequate measurements, not limitations of measurement itself. — ch. 8
95. Sound Field Management handles flexible subwoofer placement in irregular room shapes — ch. 8
96. A corporate research group that openly publishes can elevate both science and company reputation. — ch. 8
97. Industry rivals codified Harman’s research into a formal loudspeaker measurement standard — ch. 8
98. Perceptual masking hides large LP distortions that measurements reveal — ch. 8
99. Measurement axes produce low-frequency calibration errors from woofer offset and port placement — ch. 8
100. Crosstalk cancellation delivers binaural separation through loudspeakers — ch. 9
101. Mixing decisions are monitored through loudspeakers in a room. — ch. 9
102. Individualized HRTF data is required for reliable crosstalk cancellation — ch. 9
103. Listeners perceive the pitch of a bass note even when its fundamental is absent. — ch. 9
104. Mastering engineers must undo sonic artifacts introduced by flawed mixing monitors. — ch. 9
105. Cinema’s non-neutral spectral target forces engineers to compensate and varies across venues — ch. 9
106. Modern immersive audio delivers perceptual clues rather than reconstructing real sound fields — ch. 9
107. Recordings are artistic creations, with loudspeakers merely the messengers. — ch. 9
108. Binaural audio without visuals and head tracking stays internalized in the head — ch. 9
109. Crosstalk cancellation expands stereo images from ±30° to as wide as ±90° — ch. 9
110. Recording engineers preferred direct-sound fields partly to mask poor monitor loudspeakers. — ch. 9
111. Unidentified or invisible sounds are perceived as coming from behind the head — ch. 9
112. Mixing in acoustically dead rooms complicates translation to lively home listening — ch. 9
113. Personalized HRTFs improve sound externalization in binaural reproduction — ch. 9
114. Virtualized loudspeaker playback can compete with real multi-speaker systems on listener preference. — ch. 9
115. ITU and EBU listening tests differ fundamentally as relative versus absolute judgments. — ch. 9
116. Most popular-music recordings are built from close-miked or synthesized sounds, not live acoustic performances — ch. 9
117. The Auratone 5C reference speaker was objectively poor and inconsistent across samples — ch. 9
118. The science of acoustics began with concert hall reverberation theory — ch. 9
119. Mastering engineers often work in acoustically untreated domestic rooms. — ch. 9
120. Streaming loudness normalization is automating much of mastering engineering. — ch. 9
121. Professional control room designs range from dead to highly diffuse. — ch. 9
122. HRTFs are measured in anechoic space as angle-dependent transfer functions — ch. 9
123. Preferred large-venue room curves converged across 47 years of independent experiments. — ch. 9
124. Audio-video interactions grow stronger with channel count and screen size — ch. 9
125. Control-room design choices rest on preference, not validated science — ch. 9
126. Pinna, head, and torso shapes encode spatial direction into ear-canal sounds — ch. 9
127. Home and headphone listening lacks the scientific research its prevalence warrants — ch. 9
128. Listeners adapt within minutes to externalize sound even through crude transducer devices — ch. 9
129. Cinema’s X-curve standard was based on primitive measurements that ignored better available research — ch. 9
130. In-room measurement curves are dominated by reflections, not direct sound — ch. 9
131. Listeners perceptually normalize their own idiosyncratic HRTFs from birth — ch. 9
132. A single movie mix should translate across cinema, home and headphone playback — ch. 9
133. Home recording democratization raises demand for quality monitoring in untreated rooms. — ch. 9
134. Point-source mic capture loses the binaural ability to separate direct from reflected sound — ch. 9
135. Live concerts of big-name artists seek to reproduce recorded studio sound — ch. 9
136. Hearing adapts in real time to drastically modified HRTFs — ch. 9
137. Head movement resolves directional ambiguity and explains headphone sounds seeming internal — ch. 9
138. Acoustically acceptable rooms require neutral loudspeakers plus acoustical treatment — ch. 9
139. Matching acoustical and visual context yields convincing binaural externalization — ch. 9
140. Head and torso simulators capture spatial cues with microphones at eardrum locations — ch. 9
141. Modern studio mics are neutral transducers, while live mics trade neutrality for durability — ch. 9
142. Perfect HRTF matching does not guarantee better headphone sound quality — ch. 9
143. Crosstalk-cancelling filter technology has advanced with head tracking and multi-listener support. — ch. 9
144. Most US music is now produced in residential, acoustically poor rooms — ch. 9
145. A flawed consumer speaker became the recording industry’s standard near-field monitor. — ch. 9
146. Blamed loudspeaker tweeter problems may actually originate in the recording microphone — ch. 9
147. Loudspeaker directivity and early reflections affect sound quality and imaging — ch. 10
148. The phantom center image in stereo is always corrupted at the symmetrical sweet spot — ch. 10
149. Mono listening reveals a loudspeaker’s true character before stereo demo — ch. 10
150. Off-center listeners lose the phantom center image which collapses toward the nearer loudspeaker — ch. 10
151. Binaural hearing separates direct and reflected sound while monaural microphones cannot — ch. 10
152. Fully steerable loudspeaker arrays are technically feasible but priced out of existence — ch. 10
153. Stereo reproduction is an experimental basis, not a fixed system — ch. 10
154. Direct-sound-dominated rooms maximize the stereo center-image spectral distortion — ch. 10
155. Stereo presentation masks audible differences between loudspeakers found in mono. — ch. 10
156. Accurate soundstage alone cannot satisfy musically without reproduced hall reflections — ch. 10
157. Hall reverberation cloaks loudspeaker defects in live-versus-reproduced demonstrations — ch. 10
158. High broadband directivity reduces lateral reflection levels in loudspeakers — ch. 10
159. Experimental constraint forced a dipole approximation rather than true omnidirectional speakers — ch. 10
160. Lateral wall reflections arrive attenuated by inverse-square law distances — ch. 10
161. Wide-dispersion loudspeakers soften hard-panned images and reduce the center-image crosstalk dip — ch. 10
162. Microphone-array and panned recordings obey the same interchannel amplitude and time rules. — ch. 10
163. Competing recordings of the same work show enormous, sometimes poor, perspective choices. — ch. 10
164. Perceived spaciousness scales with playback level because faint reflected sounds must be audible — ch. 10
165. Amplitude panning dominates studio mixing because it gives compact, multi-listener images. — ch. 10
166. Stereo phantom center images have a spectrum dip near 2 kHz from interaural crosstalk — ch. 10
167. Stereo’s dominance stemmed from LP storage limits, not audio ideals — ch. 10
168. Wide-dispersion loudspeakers with room reflections create a you-are-there listening perspective — ch. 10
169. Movie center channels and multichannel music demand loudspeakers that perform well solo — ch. 10
170. Facing forward corrupts center-image timbre due to head-related transfer function errors — ch. 10
171. Stereo principles were understood by 1931 but waited decades for commercialization. — ch. 10
172. Room reflections mitigate the phantom-center comb-filter dip near 2 kHz. — ch. 10
173. Music industry resisted multichannel audio for cost reasons at every stage — ch. 10
174. Live-versus-reproduced demos were contrived marketing that masked genuine loudspeaker flaws. — ch. 10
175. Recordings are artistic constructions, not literal captures of live sound — ch. 10
176. Early lateral reflections are not necessarily audible problems in stereo listening — ch. 10
177. Reflected sound anchors external source localization while its absence pulls sound into the head — ch. 10
178. Overhead violin miking captures a strident 2500-5000 Hz beam requiring equalization. — ch. 10
179. Early recording technology forced performers and dead-acoustic studios as standard practice — ch. 10
180. Off-center listeners lose the stereo illusion but retain musical content — ch. 10
181. Instrument radiation patterns vary by frequency, shaping both stage reflection and audience blend — ch. 10
182. Listeners perceive the larger of two superimposed spaces in sound reproduction. — ch. 10
183. Edison staged deceptive live demonstrations to prove his phonograph was tonally transparent — ch. 10
184. Toe-in loudspeaker aiming failed to stabilize phantom center imagery off-axis — ch. 10
185. Room reflection effects are masked by spatial information already in recordings — ch. 10
186. Coincident and spaced microphone pairs encode direction into IAD or ITD cues. — ch. 10
187. Stereo and multichannel listening make listeners more forgiving of loudspeaker flaws — ch. 10
188. Stereo phantom images timbrally differ from real-source or mono center images. — ch. 10
189. Critical loudspeaker evaluation should use mono for fail-safe real-world listening — ch. 10
190. Room reflections partially fill the phantom-center spectral hole — ch. 10
191. Bass performance drives roughly 30% of overall loudspeaker sound-quality ratings. — ch. 11
192. Below the transition frequency the room, not the loudspeaker, dominates sound quality. — ch. 11
193. Speech and solo instruments reveal loudspeaker flaws least, dense broadband music most — ch. 11
194. Listeners are forgiving of headphone resonances but sensitive to bass-level air leaks. — ch. 11
195. Loudspeakers without annoying resonances tend to adapt well in real-world listening. — ch. 11
196. Standing-wave thinking applies only at low frequencies in small rooms — ch. 11
197. Car cabins create unique acoustics with no ideal listening position. — ch. 11
198. Lower Q spreads resonances wider in frequency but shortens time-domain ringing — ch. 11
199. Listeners prefer familiar distorted phantom images over technically superior real center channels — ch. 11
200. Room size and shape do not change multiple-loudspeaker sound quality ratings — ch. 11
201. Frequency response tolerances are meaningless without specifying the bandwidth of deviations — ch. 11
202. Rooms shift absolute ratings but not loudspeaker rankings in multiple-loudspeaker comparisons — ch. 11
203. Loudspeakers and rooms act as a combined system that cannot be judged separately — ch. 11
204. Small-room acoustics constrain bass quality below the Schroeder transition frequency. — ch. 11
205. High-Q resonances are rarely heard but intensely annoying when triggered. — ch. 11
206. Responsible listening tests use discriminant-selected programs and within-program comparisons — ch. 11
207. Small listening rooms lack diffuse reverberation and contain only early reflections — ch. 11
208. Timbral adaptation is a confirmed phenomenon though its mechanism remains unexplained — ch. 11
209. Blind tests show any equalization improves subjective loudspeaker ratings — ch. 11
210. Loudspeaker diaphragms support distributed resonances beyond lumped-element models — ch. 11
211. Early room reflections benefit speech intelligibility as much as raised direct sound level — ch. 11
212. A pronounced single bass resonance near 40 Hz is preferred over insufficient bass. — ch. 11
213. Room resonance excess masks loudspeaker bass deficiency to listeners — ch. 11
214. Room reflections improve the ear’s ability to hear resonances in playback. — ch. 11
215. Program material choice determines which loudspeaker or room flaws get revealed — ch. 11
216. Envelopment cues below roughly 80 Hz are hard to reproduce in small rooms. — ch. 11
217. Room differences dominate loudspeaker differences when listeners cannot adapt — ch. 11
218. Multichannel reproduction progressively masks loudspeaker resonances except low-Q ones. — ch. 11
219. Automatic EQ can create unwanted resonances by filling interference dips — ch. 11
220. Low-Q resonances are most often excited by music and most audible — ch. 11
221. Gently rising bass response is both natural and preferred in loudspeakers — ch. 11
222. Listening in large reverberant venues may compromise discernible sound qualities — ch. 11
223. Automated loudspeaker position switching improves listening-test reliability — ch. 11
224. Correlating anechoic data, room response, and blind listening tests is rare and powerful — ch. 11
225. The hearing system adapts well to phantom stereo images despite conflicting HRTF cues — ch. 11
226. Above 200 Hz the spectral peak, not the ringing, determines resonance audibility. — ch. 11
227. More playback channels increasingly mask audible loudspeaker resonances — ch. 11
228. Normal listening rooms improve rather than impair speech intelligibility — ch. 11
229. A mid-frequency off-axis sag is a common audible attribute of two-way loudspeakers. — ch. 11
230. Steady-state room curves above 400-500 Hz misrepresent perceived sound quality. — ch. 11
231. The original Schroeder constant fits small rooms better than the revised one — ch. 11
232. Dimensional room symmetry does not guarantee acoustic symmetry — ch. 11
233. Reflected sounds physically dominate what reaches listeners’ ears — ch. 11
234. Tone-control adjustments are easily heard because low-Q resonance thresholds are tiny — ch. 11
235. Well-damped low-Q resonances are easier to hear than high-Q ones. — ch. 11
236. Listeners perceptually normalize voices across changing room acoustics via direct sound and visual cues — ch. 11
237. Listeners adapt to reverberant rooms within seconds, improving speech intelligibility by 18% — ch. 11
238. The Schroeder frequency miscalculates for small furnished rooms but the transition is real — ch. 11
239. Minimum-phase loudspeaker resonances are correctable with parametric equalization. — ch. 11
240. A transition frequency separates modal from ray acoustical behavior in rooms — ch. 11
241. Randomizing lateral speaker positions averages out width-mode influences in tests — ch. 11
242. Home theater center channels are often inferior despite being the most important speaker — ch. 11
243. Recording complexity and reverberation raise the audible threshold for resonances — ch. 11
244. Acoustical interference differs per off-axis angle and is averaged out perceptually in rooms — ch. 11
245. Audible resonance data enables value engineering of cheap loudspeakers — ch. 11
246. Reverberation extends the fusion zone in which reflections merge with the direct sound — ch. 12
247. Diffusor effectiveness in small listening rooms lacks subjective validation — ch. 12
248. Musical program material flattens reflection threshold curves compared to speech — ch. 12
249. Reflection control reduces reflected energy either by absorption or by scattering. — ch. 12
250. Reflections that appear as destructive comb filtering actually create perceived spaciousness. — ch. 12
251. Fibrous absorbers become ineffective below roughly a quarter-wavelength thickness. — ch. 12
252. Precedence effect threshold curves hold stable across very different listening environments — ch. 12
253. Ceiling reflections are as detectable as lateral ones despite weak binaural cues — ch. 12
254. Real-room reflections are attenuated and delayed, not equal-level and immediate. — ch. 12
255. Steady-state frequency curves misrepresent how transient music interacts with reflections. — ch. 12
256. Humans are least sensitive to delayed sounds emerging from the same speaker — ch. 12
257. Natural room reflections never exceed direct sound, so precedence always holds — ch. 12
258. Later-arriving reflections within the fusion zone do not create separate images. — ch. 12
259. Multichannel and immersive audio reduce the perceptual importance of small-room reflections. — ch. 12
260. Detecting reflected sound depends heavily on the continuity of the source signal — ch. 12
261. Master recordings must be evaluated in reflective rooms to translate to consumer listening — ch. 12
262. ETC displays can misreport reflection levels by about 20 dB versus audibility — ch. 12
263. Acoustical materials alter reflection spectra, invalidating broadband measurements for audibility — ch. 12
264. Perceptual changes detected at threshold become desirable when heard as image broadening — ch. 12
265. The breakdown of precedence yields a subordinate second image, not equal images. — ch. 12
266. Precedence fusion is not masking; all reflections remain audible — ch. 12
267. Room reverberation barely affects early reflection audibility but strongly elevates late-reflection thresholds — ch. 12
268. Haas measured how much louder a delayed sound could be before dominating localization — ch. 12
269. Audible room deficiencies are rarely caused by comb filtering. — ch. 12
270. Delayed lateral sound can exceed direct sound by 10 dB before perceived equally loud — ch. 12
271. Diffusing surfaces may not reduce perceived reflection loudness as expected — ch. 12
272. Standard octave-band smoothing hides the fine structure of comb-filter patterns. — ch. 12
273. Phantom stereo images resist lateral-reflection interference as well as real images do — ch. 12
274. The precedence effect fusion interval lengthens with signal continuity — ch. 12
275. Listeners can indicate preferred levels of individual reflected sounds — ch. 13
276. Elevation localization relies on pinnae spectral cues encoded as HRTFs — ch. 13
277. Adding rear speakers at matching angles does not improve spatial illusion — ch. 13
278. Spaciousness dominates pleasantness more than sound quality does. — ch. 13
279. Loudspeaker angular separation, not rear placement, drives spatial immersion — ch. 13
280. Perceived quality is judged as deviation from an ideal amount. — ch. 13
281. Elevation cues involve increased 7-8 kHz and decreased 12 kHz energy — ch. 13
282. Lateral reflections near 60 degrees matter while front-rear reflections do little. — ch. 13
283. Atmos up-firing speakers exploit ceiling bounce because elevation cues are high-frequency. — ch. 13
284. Listeners tolerate second images in music because spaciousness outweighs them. — ch. 13
285. Listeners prefer reverberation times of 1-1.1 s for piano in living-room-sized spaces — ch. 13
286. Music benefits from dedicated side channels at ±60 degrees — ch. 13
287. Multichannel audio delivers directional reflections and long delays matching large venues — ch. 13
288. Side-wall reflections aid spatial impression while front and rear early reflections do little — ch. 13
289. Acoustical interference dips are too unstable to be evolutionary localization cues — ch. 13
290. Frequency-dependent interaural cross-correlation measures sound-field reconstruction fidelity. — ch. 13
291. Music listeners prefer reflections far stronger and later than small rooms provide. — ch. 13
292. Fewer-channel arrays were judged against a 24-speaker reference for envelopment impairment — ch. 13
293. Horizontal localization is most acute straight ahead and degrades sharply to the sides. — ch. 13
294. Reflections arriving from about 50-70 degrees lateral maximize perceived spaciousness. — ch. 13
295. Larger recorded spaces perceptually dominate smaller playback spaces — ch. 13
296. Elevation localization rests on spectral recognition of familiar sounds, not spatial cues. — ch. 13
297. Perceived loudspeaker sound quality depends only on amplitude responses — ch. 13
298. Multiple listeners off the sweet spot need extra channels for envelopment. — ch. 13
299. Natural room reflections are too weak and early to please listeners of reproduced speech. — ch. 13
300. Monaural reproduction conveys reverberation only as a time-domain effect without spatial envelopment — ch. 13
301. Side-positioned surround loudspeakers are preferred over rear placement, known since 1971 — ch. 13
302. Elevation localization is a timbral recognition task driven by resonant peaks — ch. 13
303. Individualized elevation cue perception makes listener-specific calibration permanent. — ch. 13
304. True envelopment needs reflections delayed beyond 80 ms, impossible in small rooms alone — ch. 13
305. Horizontal localization uses binaural cues while vertical localization does not — ch. 13
306. Spaciousness comes from natural room reflections, recorded multichannel reflections, or both. — ch. 13
307. Listener expectations, not acoustic cues alone, drive perceived spatial location. — ch. 13
308. THX-certified dipole surrounds varied wildly in measured sound quality — ch. 14
309. Cinema, not music, has driven every expansion of audio channel count — ch. 14
310. Bass management lets small loudspeakers deliver full-range sound — ch. 14
311. Low frequencies travel through structure walls and floors more than highs — ch. 14
312. Smaller rooms drastically worsen envelopment at off-center seats — ch. 14
313. Signal-adaptive matrix steering works only for single moving images — ch. 14
314. A multichannel system need not compromise stereo quality — ch. 14
315. Marketing fads can override objective engineering in product design — ch. 14
316. Listener-level channels, not height channels, drive spaciousness and envelopment — ch. 14
317. Room curves show loudspeaker results, not targets worth equalizing toward — ch. 14
318. Toe-in aiming of front loudspeakers minimizes problematic side-wall reflections — ch. 14
319. Downmixing across channel counts remains an unresolved delivery problem. — ch. 14
320. Dolby’s 100 Hz Atmos crossover risks localizing subwoofers but is accepted for simplicity — ch. 14
321. Electroacoustic reverberation enhancement systems can invisibly reshape hall acoustics per performance. — ch. 14
322. Multichannel audio generates both localized off-screen sounds and convincing envelopment. — ch. 14
323. LARES enhancement was imperceptible during music but obvious during pauses. — ch. 14
324. Most recordings are abstract constructions, not accurate reproductions of live music. — ch. 14
325. THX-type dipole surrounds produced irregular mid-frequency depressions, not neutral nulls — ch. 14
326. THX dipole surround speakers degraded direct sound while failing to create genuine diffusion. — ch. 14
327. Four mic-speaker pairs can transform a room’s perceived acoustics into a hall. — ch. 14
328. Home theater centers must acoustically match L and R speakers lacking cinematic identical units — ch. 14
329. Most commercial Atmos music mixes are embellished stereo rather than true multichannel. — ch. 14
330. Object-based audio sacrifices sound quality but suits transient effects; fixed images suit music. — ch. 14
331. The center channel carries most dialog and on-screen sound in movies — ch. 14
332. Film mixes with expanded dynamic range strain dialog intelligibility — ch. 14
333. Constant beamwidth transducers deliver uniform sound levels over large areas — ch. 14
334. Furniture and drapes alone usually achieve the 0.3-0.4 s domestic reverberation target — ch. 14
335. The LFE channel was created to handle blockbuster bass beyond 40 Hz. — ch. 14
336. Immersive music masters have no stable target playback format. — ch. 14
337. A mono center channel suffices because vision dominates perceived sound location. — ch. 14
338. Quadraphonic forced vinyl playback bandwidth to 50 kHz, improving LP quality — ch. 14
339. Bipole but not dipole designs give surround channels needed coverage — ch. 14
340. The dipole surround era ended because it was not scientifically sound — ch. 14
341. Opposite-wall reflections compensate for surround propagation loss at no cost — ch. 14
342. Multichannel spaciousness requires bypassing inverse-square-law propagation loss — ch. 14
343. Early side-wall reflections range neutral to beneficial with well-designed loudspeakers — ch. 14
344. Receiver bass-management implementations vary, causing differing user experiences. — ch. 14
345. Phantom imaging lets object-based audio create many locations from few loudspeakers — ch. 14
346. Immersive systems could cheaply implement room reverb enhancement but none do. — ch. 14
347. Envelopment requires a center channel instead of a symmetric front-back array. — ch. 14
348. Stereo upmixing quality varies because it depends on the pairing of recording and upmixer. — ch. 14
349. Amplitude panning fails front-to-back because ear placement suits horizontal localization. — ch. 14
350. Matrixed quadraphonic crosstalk made localization unstable with head movement — ch. 14
351. Renderers use metadata to adapt recordings to any loudspeaker configuration. — ch. 14
352. Dipole surrounds only worked for one row of listening positions — ch. 14
353. Multiple independently-processed subwoofers tame room resonances for wider listening areas. — ch. 14
354. Physically separated MTM drivers acoustically interfere off-axis because both radiate overlapping high frequencies — ch. 14
355. Sound-power specifications only make sense in diffuse fields impossible in small rooms — ch. 14
356. Bass management reroutes low frequencies from small speakers to shared subwoofers. — ch. 14
357. Decorrelation of surround channels solved in-head localization in home theaters. — ch. 14
358. The listening room’s influence on sound diminishes as channel count increases. — ch. 14
359. THX dipole surrounds were bidirectional out-of-phase pairs, not true dipoles — ch. 14
360. Surround loudspeakers close to listeners become distractingly localizable. — ch. 14
361. Cinema playback levels are calibrated with pink noise and C-weighting. — ch. 14
362. Full-height line sources halve the off-center damage to envelopment — ch. 14
363. Upmixers that overuse the center channel degrade the stereo music soundstage. — ch. 14
364. The ear’s sound-level-dependent nonlinearities cannot be substituted or corrected for — ch. 15
365. Diffusing surfaces serve performance spaces, not home reproduction rooms. — ch. 15
366. Large cone diaphragms develop breakup resonances at high frequencies that color sound — ch. 15
367. Consumer loudspeaker distortion is masked at normal listening levels. — ch. 15
368. A-weighted measurements ignore low-frequency energy that unweighted SPL captures. — ch. 15
369. Accurate reproduction requires flat response at near-original playback levels — ch. 15
370. Flutter echoes can be detected by a handclap test while others listen. — ch. 15
371. Graphs in audio reviews can deceive by manipulating axis scaling. — ch. 15
372. Treble boost in loudness controls damages sound quality unnecessarily — ch. 15
373. Equal-loudness contours were first measured using 1 kHz reference tones and phons — ch. 15
374. Large radiating surfaces become highly directional at high frequencies — ch. 15
375. Car road noise exceeds music spectra below about 200 Hz — ch. 15
376. Time and frequency resolution cannot both be improved simultaneously — ch. 15
377. Vinyl’s own asymmetrical distortion confounded early polarity-audibility tests — ch. 15
378. High-power loudspeakers often trade timbral accuracy, while accurate ones are limited in level — ch. 15
379. Steady-state frequency response is the reliable indicator of audible room resonances — ch. 15
380. Sound reflecting off a hard boundary has zero particle velocity — ch. 15
381. Equal-loudness contour measurement evolved from anechoic pure tones to reflective-space noise bands — ch. 15
382. Conventional distortion metrics cannot predict human response to music or movies — ch. 15
383. Low frequencies produce tactile whole-body sensation while higher frequencies drive pitch perception — ch. 15
384. Loudness depends on frequency, angle, duration, and envelope, not just level — ch. 15
385. Diffusers manipulate only part of the spectrum and can act as absorbers when fabric-covered — ch. 15
386. Listeners prefer flat amplitude response but are insensitive to phase shift — ch. 15
387. Audible acoustic polarity effects require the ear’s asymmetric detection process — ch. 15
388. Lower-than-reference listening levels require accessible bass tone controls for satisfaction. — ch. 15
389. Home theater owners routinely reduce volume by 10 dB or more — ch. 15
390. Occupational hearing guidelines allow damage, not prevention of loss. — ch. 15
391. Different equal-loudness contour studies disagree substantially in shape — ch. 15
392. Simple loudness-compensation bass boosts cannot work for dynamic-range music — ch. 15
393. Nonlinear distortion adds frequencies that were not in the original signal — ch. 15
394. Audiophile hardware that omits tone controls harms listeners’ ability to improve sound. — ch. 15
395. Loudness compensation reduces effectively to a bass tone control — ch. 15
396. A ten-phon level reduction halves perceived loudness — ch. 15
397. Standing waves form when wavelengths match room dimensions — ch. 15
398. Standing waves create loudness dips at room midpoints — ch. 15
399. Diffuser depth sets a lower frequency below which no scattering occurs. — ch. 15
400. A room appearing to ring at many frequencies actually has only one dominant resonance. — ch. 15
401. Percentage distortion metrics include inaudible masked components and mispredict perceived quality — ch. 15
402. Frequency and time domain representations equivalently define linear loudspeaker behavior — ch. 15
403. Audio distortion arises from level-dependent nonlinearity in the device’s transfer function — ch. 15
404. Half-wave rectification in the inner ear does not make polarity reversal audible — ch. 15
405. Music’s dense spectrum masks its own distortion products. — ch. 15
406. Woofer excursion limits constrain dynamic range more than tweeter capabilities do — ch. 15
407. Wall projections must exceed one-seventh wavelength to scatter sound usefully — ch. 15
408. Frequency response is the single most important measurable parameter of audio devices. — ch. 15
409. Doubling perceived loudness requires a 10 dB increase. — ch. 15
410. Hearing loss widens critical bands and alters music perception itself — ch. 15
411. Loud bass masking spreads upward to cover the voice frequency range — ch. 15
412. Low-frequency phase shift accumulates massively across every stage of the signal chain — ch. 15
413. No time-frequency analysis method has psychoacoustic validation for room decay. — ch. 15
414. Hearing spans a pressure range greater than a million to one — ch. 15
415. Upward masking makes intermodulation difference tones more audible than harmonics — ch. 15
416. 16-bit CD audio suffices for most program material while 24-bit exceeds delivery needs — ch. 15
417. As wavelength shrinks below diaphragm size, speakers beam and off-axis sound diverges spectrally — ch. 15
418. Speaker specs like ±3 dB 80 Hz-18 kHz convey almost no useful information — ch. 15
419. Spectral variations inside one critical band alter perceived timbre — ch. 15
420. Panel loudspeakers’ low-mass diaphragms do not actually respond faster than conventional coils — ch. 15
421. Minimum-phase reasoning lets frequency responses alone reveal room resonance behavior. — ch. 15
422. Phase shift is largely inaudible for reproduced music in reflective rooms — ch. 15
423. Consumers prefer boosted bass, a forgivable audible sin — ch. 15
424. Playback in noisy environments is shrinking audio dynamic range. — ch. 15
425. Room curve variations across control rooms distort recordings’ spectral balance — ch. 15
426. Measuring power compression properly needs broadband program-like conditioning signals — ch. 15
427. Subwoofers radiate omnidirectionally because their wavelengths far exceed diaphragm size — ch. 15
428. Heating voice coils raises resistance and lowers transducer output — ch. 15
429. High frequency resolution in waterfalls forces poor time resolution that misrepresents room decay. — ch. 15
430. Technical measurement is necessary for subjective audio judgments to be meaningful. — ch. 15
431. Fletcher and Munson’s equal-loudness data are no longer trusted — ch. 15
432. Amplitude bumps in transducers imply predictable phase anomalies and time ringing. — ch. 15
433. Group delay detection threshold is 1.6-2 ms — ch. 15
434. High-frequency loss with distance provides a perceptual cue for judging sound source distance — ch. 15
435. Recording studio background noise should approach the hearing threshold — ch. 15
436. NC curves originated to rate speech intelligibility, not listener satisfaction — ch. 15
437. Modern crossovers no longer produce audible artifacts, defeating single-driver speaker advocates — ch. 15
438. Frequency response is the principal determinant of loudspeaker sound quality. — ch. 15
439. No accepted method rates subjective acceptability of ambient noise spectra — ch. 15
440. Equal-loudness contours are a fixed property of human hearing — ch. 15
441. Phonograph playback added high percentage distortion that stayed inaudible under music — ch. 15
442. Subjective judgment remains the ultimate reference for loudness measurement schemes — ch. 16
443. Audio electronics can introduce flaws that subjective reviewers misread as virtues — ch. 16
444. Consumer Reports killed its loudspeaker reviews after research disproved their methods — ch. 16
445. A single gatekeeper listener biases entire group toward his preferences — ch. 16
446. A blind-versus-sighted test was designed to expose the influence of visual bias — ch. 16
447. Mechanized positional substitution enabled fast double-blind loudspeaker product testing — ch. 16
448. Hearing-normal listeners give far more consistent loudspeaker quality ratings. — ch. 16
449. Multiple listening positions must be rotated to average out room bass variations. — ch. 16
450. Published loudspeaker impedance ratings rarely represent actual frequency response — ch. 16
451. European multichannel loudness experiments matched listener judgments to model predictions. — ch. 16
452. Louder sounds are perceived as having more bass and bias subjective comparisons. — ch. 16
453. Hearing loss impairs spatial sound separation, not just frequency detection. — ch. 16
454. Stereo playback masks differences between loudspeakers with room reflections — ch. 16
455. Turntable movers cheaply enable blind loudspeaker testing for most use cases. — ch. 16
456. Speaker wire resistance is negligible compared to tube amplifier output impedance — ch. 16
457. Musicians make poor or unreliable subjective loudspeaker evaluators — ch. 16
458. Sighted evaluations stress trained listeners who no longer accept visual bias. — ch. 16
459. Measured data can challenge subjective impressions because conditions differ — ch. 16
460. Loudspeaker voicing is a guessing game born of poor engineer-consumer communication — ch. 16
461. A-weighting won general acceptance while B-weighting was abandoned — ch. 16
462. Knowing product identity biases listening judgments through the placebo effect — ch. 16
463. Listeners elaborate on flaws but give short praise to good products — ch. 16
464. Psychoacoustic loudness models cannot accurately predict individual listener responses — ch. 16
465. No single loudness meter can capture subjective loudness of varying program material across environments — ch. 16
466. Familiar repeated test music reveals loudspeaker flaws that unfamiliar excerpts cannot — ch. 16
467. Sighted listeners become ‘deaf’ to program-dependent sound differences — ch. 16
468. Reliable panel listeners show low variance and wide rating ranges — ch. 16
469. Blind tests group listeners by judgment variability to reveal hearing effects — ch. 16
470. Averaged listener ratings can hide hearing-loss-driven individual disagreement — ch. 16
471. Subjective sound quality is authoritative and measurements must explain it — ch. 16
472. Program material and recording quality strongly determine audibility of speaker defects — ch. 16
473. Belief systems reject disconfirming evidence rather than revising theories — ch. 16
474. Damping factor is the standardized specification for amplifier output impedance — ch. 16
475. Group listener sessions bias subjective loudspeaker ratings through social signaling — ch. 16
476. Most amplifiers drive 4-ohm minima though low-impedance loads trigger limiting — ch. 16
477. Sighted listeners recall prior ratings and ignore audible position differences — ch. 16
478. Screen fabric must lose under one dB yet remain porous enough to conceal speakers — ch. 16
479. Cultural and age biases in sound preference are minimal, except for hearing degradation — ch. 16
480. Standard studio calibration levels are measurably too loud for typical listeners — ch. 16
481. Speaker wire and cables show negligible audible differences under controlled tests — ch. 16
482. Hearing-impaired listeners give inconsistent sound-quality ratings unlike normal-hearing subjects — ch. 16
483. Critics reject preference testing as mere taste, demanding realism or accuracy instead — ch. 16
484. Low-frequency performance drives roughly 30 percent of sound quality ratings — ch. 16
485. Comparing three or four loudspeakers at once best exposes timbral differences — ch. 16
486. Internet audio reviews lack bias control and thus unreliable evidence — ch. 16
487. Tone controls are a rational fix for recording-to-recording spectral variation — ch. 16
488. Most reproduced program content is effectively monophonic — ch. 16
489. Well-designed loudspeakers are recognized by ordinary customers only under valid comparison conditions — ch. 16
490. Subjective listening remains the final authority over measurement validity. — ch. 16
491. Recordings with broadband spectral variations still reliably reveal loudspeaker resonances — ch. 16
492. Listeners perceptually normalize familiar rooms to judge loudspeakers clearly — ch. 16
493. Listener fatigue objections can be answered by self-paced switch testing — ch. 16
494. Hi-fi enthusiasm predicts listening reliability better than musical training does — ch. 16
495. Most loudspeaker-wire mythology has no physical basis — ch. 16
496. The ITU loudness standard uses K-weighting with a 4 dB high-frequency head boost. — ch. 16
497. Most loudspeaker reviews rely on sighted listening susceptible to bias — ch. 16
498. Audio industry product sign-offs relied on executive taste, not blind testing — ch. 16
499. Formal listener training plus experience yields the highest rating reliability — ch. 16
500. High-end audio wire exploits expectation bias rather than real physics — ch. 16
501. Head-tracking with measured impulse responses strongly improves sound externalization — ch. 16
502. Preferred TV and film dialog playback levels vary widely across listeners. — ch. 16
503. Random loudspeaker repositioning across listening seats eliminates room-position bias — ch. 16
504. Naive and trained listeners agree closely on loudspeaker quality ratings — ch. 16
505. Visual appearance of loudspeakers shifts listener preference ratings — ch. 16
506. Loudness perception is robust enough that precise weighting matters little in practice. — ch. 16
507. Listeners judge loudspeakers equally well on studio-produced popular music — ch. 16
508. Constant errors normalize away in comparative loudspeaker tests — ch. 16
509. Declared normal hearing can still hide degraded sound-quality opinions. — ch. 16
510. Subjective listening opinions shift with time and new information — ch. 16
511. Sub-2-ohm speaker designs caused the amplifier differences reviewers praised — ch. 16
512. Listener expertise and gender shape rating patterns in loudspeaker evaluations. — ch. 16
513. Engineers distrusting blind tests converted upon seeing correlations with their measurements. — ch. 16
514. Buffered listening environments mask off-axis loudspeaker flaws and bias evaluations — ch. 16
515. Listener preference is driven mostly by timbral neutrality across the listening window — ch. 17
516. Early loudspeaker preference studies were too crude to validate any measurement model — ch. 17
517. Statistically confirmed listener preference for neutral timbre with deep bass — ch. 17
518. Consumer Reports rated loudspeakers using sone-converted sound power against an ideal target — ch. 17
519. Frequency-dependent acoustic power output is a loudspeaker’s most audible performance aspect — ch. 17
520. Room acoustics dominate perceived bass response below roughly 250 Hz — ch. 17
521. Sound power alone cannot predict listener preference for loudspeakers — ch. 17
522. Perceived spectral balance matches on-axis response more than sound power or room curve — ch. 17
523. Loudspeaker resonances are the primary cause of poor sound quality. — ch. 17
524. Preference models trained on homogeneous product sets may not generalize — ch. 17
525. On-axis flatness and smooth off-axis response predict 75% of listening preference — ch. 17
526. Fine-grained anechoic measurement statistics can near-perfectly predict listener preference rankings — ch. 17
527. Smoother, flatter, wider-bandwidth on-axis curves predict higher subjective loudspeaker ratings. — ch. 17
528. Sound power alone does not predict loudspeaker sound quality. — ch. 17
529. Consumer Reports’ accuracy scores inversely correlated with actual listener preferences. — ch. 17
530. Trained listeners can verbally connect sound preference to measurable on-axis and listening-window curves — ch. 17
531. Trained listeners can draw accurate spectral-balance curves of what they hear — ch. 17
532. Predicting subjective loudspeaker preference from measurements was long considered impossible — ch. 17
533. The listening room, not the loudspeaker, determines perceived bass quality. — ch. 17
534. Home listening rooms show RT of 0.2–0.4 seconds with no diffuse field — ch. 18
535. Sound angled into absorbers absorbs more by traveling through more material — ch. 18
536. A well-furnished domestic room can already provide acceptable reverberation times for listening. — ch. 18
537. Far field onset distances vary widely by source size and wavelength — ch. 18
538. Untrained listeners in method-of-adjustment tests prefer the boosted “happy face” spectrum. — ch. 18
539. Consumer tone control use disrupts program translation across systems. — ch. 18
540. Staggering absorption zones on facing walls suppresses flutter echoes in listening rooms. — ch. 18
541. Industry-internal sound translation may be arbitrary but public translation cannot be — ch. 18
542. Statistical acoustics and classical critical distance do not apply in small rooms — ch. 18
543. Only sound quality and spatial effects can be physically controlled in recordings — ch. 18
544. The cinema ‘closed loop’ of sound translation has broken as viewing fragmented — ch. 18
545. Common tall loudspeakers are not true line sources — ch. 18
546. Absorption coefficients above 1.0 reveal the spec is not a simple percentage. — ch. 18
547. Room diffusion is not required for perceived spaciousness — ch. 18
548. Fiberglass density barely affects absorption but strongly affects mechanical strength — ch. 18
549. Cinema RT targets balance dialog clarity against realistic hall ambience. — ch. 18
550. A room can sound anechoic and reverberant simultaneously — ch. 18
551. Anechoic loudspeaker data reliably predict in-room high-frequency response above 500 Hz. — ch. 18
552. Random-incidence absorption coefficients fail to predict actual reflected spectra — ch. 18
553. Room size does not alter steady-state curves above 400 Hz — ch. 18
554. Equalization cannot fix loudspeaker directivity problems because it only changes frequency response. — ch. 18
555. Standing versus seated position changes perceived sound quality only insignificantly — ch. 18
556. Multichannel recording content masks room acoustics and loudspeaker resonances — ch. 18
557. Home-room ‘reverberation time’ actually measures reflection or resonance decay — ch. 18
558. Home theater RT targets demand costly low-frequency absorbers yet ignore the resonance problem. — ch. 18
559. Desirable room acoustics can be encoded and delivered digitally rather than built — ch. 18
560. Curved, Legendre-shaded line arrays exploit floor reflections to maintain constant beamwidth at all frequencies — ch. 18
561. A single steady-state room curve cannot represent what two ears and a brain perceive. — ch. 18
562. Bass traps’ inadequacy pushed Toole toward multi-subwoofer mode control. — ch. 18
563. Mini-reflections perceptually add up beyond what visual reflection analysis predicts — ch. 18
564. Equalizing for a flat in-room response requires adding a high-frequency boost. — ch. 18
565. Influential early analysis found truncated line sources have little to recommend them — ch. 18
566. Excessive absorption can degrade speech intelligibility — ch. 18
567. Near-field listening removes room reflections that mask stereo colorations — ch. 18
568. Near-field sound measurement is unreliable when multiple source parts radiate simultaneously — ch. 18
569. Carpet underlay type determines whether flooring absorbs sound at all — ch. 18
570. Sound power predicts room response for omnidirectional speakers while directivity shapes room curves — ch. 18
571. A single boundary reflecting sound off an omnidirectional source creates frequency-dependent interference lobes — ch. 18
572. Seat-caused acoustical interference eludes equalization and often goes unnoticed by listeners — ch. 18
573. Listeners must sit at least three wavelengths from diffusers to avoid coloration — ch. 18
574. Randomly spaced hemi-cylinder diffusers work far better than contiguously placed ones — ch. 18
575. Minimizing floor-reflection dips in measured curves produced no audible improvement — ch. 18
576. Loudspeaker evaluation requires mono, while enjoyment happens in multichannel — ch. 18
577. Fiberglass reflection depends on angle and frequency, not density — ch. 18
578. Smooth equalized room curves often signal degraded sound quality — ch. 18
579. Too much uncorrelated rear-wall diffusion scrambles center imaging — ch. 18
580. Spatial averaging of measurements suppresses interference artifacts while preserving spectral information — ch. 18
581. Sighted evaluations of acoustical rooms are biased by visual distinctiveness — ch. 18
582. Removing floor reflections makes sound unnatural to human listeners — ch. 18
583. Constant-beamwidth-transducer speaker arrays hold stable loudness across listening distance — ch. 18
584. Harman’s calibration target curve encoded deliberately tilted in-room response, not flat room response — ch. 18
585. Above 500 Hz room curves are predictable from anechoic loudspeaker data — ch. 18
586. Sound power is a poor estimator of bass performance in real rooms. — ch. 18
587. Loudspeaker off-axis response dominates in-room energy at the listening position. — ch. 18
588. Commercial loudspeaker engineering requires translation across varied sources and listeners — ch. 18
589. On-axis frequency response cannot predict in-room measurements but does predict perceived sound. — ch. 18
590. Early reflections within 30-40 ms improve speech intelligibility — ch. 18
591. Concert halls need 1–2 seconds of reverberation balancing loudness against clarity — ch. 18
592. Absorber performance at specific incidence angles matters more than standardized diffuse-field ratings. — ch. 18
593. In rooms the inverse-square law applies only to the direct sound — ch. 18
594. Tall speakers with stacked woofers are not true line arrays — ch. 18
595. Anechoic far-field measurements need at least two meters of distance — ch. 18
596. Diffusers mainly attenuate specific reflections rather than create diffuse fields — ch. 18
597. Room treatment absorbers receive sound at 45 to 60 degrees incidence — ch. 18
598. Even expert engineers are biased by non-auditory factors in loudspeaker evaluation — ch. 18
599. Elevated microphones above 400 Hz congregate, reducing seat-related measurement anomalies — ch. 18
600. Mid-field listening includes room sound without needing to eliminate the listening space — ch. 18
601. Fabric wall coverings often ruin acoustic design despite being advertised as transparent — ch. 18
602. Binaural and crosstalk-cancelled delivery may finally make multichannel practical — ch. 18
603. Room reflectivity at low frequencies determines bass elevation in measured steady-state curves — ch. 18
604. Floor reflections evolved as a constant cue for spatial judgment — ch. 18
605. Critical distance is ill-defined in small rooms because short reverberation times fail steady state — ch. 18
606. Decorative stretched fabric over empty walls turns a room acoustically dead. — ch. 18
607. Air space behind absorbing panels cheaply improves absorption performance — ch. 18
608. Diffusion terminology is routinely misapplied to small rooms — ch. 18
609. Effective sound diffusers must be physically comparable in size to the waves they scatter — ch. 18
610. Perfect diffusion is an unattainable ideal in real rooms — ch. 18
611. Anechoic early-reflections data predict steady-state room curves across rooms and sample variations. — ch. 18
612. The Harman target curve applies only below the transition frequency. — ch. 18
613. The audio industry still lacks a scientific foundation for format decisions — ch. 18
614. Most commercial diffusers are designed for looks rather than measurable acoustic performance — ch. 18
615. No single acoustic treatment satisfies because satisfaction is multidimensional — ch. 18
616. Deep broadband diffusers can create a 30 dB immediate reflection drop — ch. 18
617. Near field and far field mislabel room zones better called direct versus reflected-sound dominant — ch. 18
618. Multiple subwoofers can replace bass traps and even improve efficiency — ch. 18
619. The ITU-R BS.1116 standard is routinely misapplied to loudspeaker evaluation rooms. — ch. 18
620. Conventional and bookshelf loudspeakers are engineered for free-standing placement — ch. 19
621. Rear-boundary reflections add decorrelated sound that degrades imaging and soundstage — ch. 19
622. Spatial averaging reveals boundary effects hidden by standing waves — ch. 19
623. Room standing waves mask the adjacent-boundary effect even after averaging. — ch. 19
624. Front loudspeakers are designed without regard for their boundary settings — ch. 19
625. The cancellation dip shifts to higher frequencies and weakens as measurement moves off axis. — ch. 19
626. Greater loudspeaker-wall separation shifts the adjacent-boundary dip to lower frequencies — ch. 19
627. A flat-response speaker still shows boundary-induced frequency changes in room — ch. 19
628. Comparative measurements remain reliable even without absolute low-frequency accuracy — ch. 19
629. Wall mounting creates a comb-filter cancellation dip whose frequency scales with baffle size. — ch. 19
630. Bipole surround loudspeakers radiate hemispherically to deliver similar direct sound to all listeners — ch. 19
631. Controlled measurements confirm the theoretical boundary-gain relationships at low frequencies — ch. 19
632. Boundary-image relationships hold only when wavelengths exceed source size and separation — ch. 19
633. Spatial averaging and in-situ power measurement reveal identical boundary effects — ch. 19
634. Closing off cavity openings with hard material outperforms absorbing fill. — ch. 19
635. Adjacent boundaries alter radiated sound power via acoustical radiation resistance — ch. 19
636. Low-frequency room response depends on woofer distances to floor and walls — ch. 19
637. Soffit mounting in control rooms is a non-optimal corruption of half-space mounting — ch. 19
638. Boundary reflections create acoustical images that halve the radiation solid angle — ch. 19
639. Boundary distances tuned to be unequal and non-multiples minimize frequency-response variations — ch. 19
640. Boundary placement boosts low-frequency output by 6 dB per solid-angle halving. — ch. 19
641. Sitting close to a rear wall creates early strong reflections that corrupt perceived sound — ch. 19
642. Reflections from adjacent walls create destructive interference nulls at one-half wavelength spacing. — ch. 19
643. Smaller drivers radiate more omnidirectionally at a wider frequency range — ch. 19
644. Flush-mounting in a wall boosts bass output of a loudspeaker not designed for it. — ch. 19
645. Audible resonance decay thresholds rise sharply as frequency decreases — ch. 20
646. Resonance detection thresholds rise with higher Q and lower frequency — ch. 20
647. Processing corrected at discrete seats also improves sound between and around those seats. — ch. 20
648. Simultaneous subwoofer outputs cannot be predicted from individually measured responses — ch. 20
649. Low, isolated axial modes dominate room problem-solving attention — ch. 20
650. Computer-assisted search is needed to optimize bass in non-rectangular rooms — ch. 20
651. Optimized room-dimension ratios may not reliably produce better-sounding rooms. — ch. 20
652. Opposing in-phase subwoofers cancel odd-order axial modes but amplify even-order ones. — ch. 20
653. Additional distributed subwoofers with optimization outperform EQ while using less power. — ch. 20
654. Bass level errors cause perceived treble excess and vice versa — ch. 20
655. Subwoofer placement severely impacts the electrical power needed for equal low-bass output. — ch. 20
656. Optimal room ratios as originally conceived are irrelevant to sound reproduction — ch. 20
657. Absorption dampens modes and enhances any additional room remedies — ch. 20
658. Delayed, inverted subwoofer arrays can cancel standing waves in rectangular rooms — ch. 20
659. Resonant peaks bother more listeners than nulls because they occupy most of the room — ch. 20
660. Equalization and listener repositioning can produce nearly identical results for room modes. — ch. 20
661. Corner subwoofer placement maximizes bass efficiency but worsens seat-to-seat consistency. — ch. 20
662. Listeners respond to resonance spectral prominence, not decay rate reduction — ch. 20
663. Commercial room-calibration algorithms vary so widely that results are not directly comparable. — ch. 20
664. Positional equalization finds seating spots weakly coupled to resonances — ch. 20
665. Non-parallel walls do not eliminate room modes — ch. 20
666. Room modes being minimum-phase means fixing the spectral bump also fixes the ringing — ch. 20
667. MSV, MOL, and VSA are the formal metrics for evaluating multi-subwoofer bass. — ch. 20
668. Subwoofer arrays can be time-aligned and equalized to minimize seat-to-seat bass variation — ch. 20
669. Powered subwoofer hardware can be repurposed as active bass absorbers — ch. 20
670. Higher-Q resonances become less audible because music rarely energizes them — ch. 20
671. Room pressurization is a compliance effect that fades in unsealed rooms — ch. 20
672. Electronic multi-subwoofer mode control excels because it benefits many listeners at once. — ch. 20
673. Moving a subwoofer away from a boundary toward a null reduces modal energy room-wide. — ch. 20
674. Modal frequency resonance is position-independent while coupling is position-dependent — ch. 20
675. Rectangular rooms allow predicting low-frequency modal behavior in advance — ch. 20
676. Equalization and mode cancellation both reduce bass resonance ringing despite different mechanisms — ch. 20
677. Double bass arrays keep high efficiency despite half the units cancelling — ch. 20
678. Waterfall diagrams alone poorly estimate the audibility of resonances — ch. 20
679. Resonance Q factors below about 16 are subjectively imperceptible to listeners. — ch. 20
680. Axial room modes can be predicted from room dimensions alone — ch. 20
681. Adding extra subwoofers rarely improves bass without controlled placement — ch. 20
682. A doorway’s flex reduces wall stiffness only below 50 Hz without harming sound — ch. 20
683. High-resolution measurement and matched Q are required for effective modal EQ. — ch. 20
684. Waterfall measurements reveal no information beyond what frequency response curves provide. — ch. 20
685. Corners are never modal nulls, so corner placement is robust. — ch. 20
686. Equalization masks a mode’s audibility but only for reproduced sound. — ch. 20
687. Bass-region reverberation-time measurements reflect resonance ringing, not reflected sound — ch. 20
688. Source and receiver placement effects on modes occur at all frequencies — ch. 20
689. A sharp resonant peak in a room’s steady-state curve predicts prolonged bass ringing. — ch. 20
690. Acoustical treatment historically meant absorption, favoring dead rooms — ch. 20
691. Respected researchers disagree on optimal room ratios, undermining confidence in the concept. — ch. 20
692. Reducing energy in a single problem mode lowers seat-to-seat response variance. — ch. 20
693. Spatial low bass below 50-63 Hz has an audible directional cutoff — ch. 20
694. Notching a room mode reduces woofer distortion and lets louder playback — ch. 20
695. Design priorities determine which subwoofer-seating configuration optimizes a room. — ch. 20
696. Bolt’s room-ratio studies targeted reverberation chambers, not listening rooms — ch. 20
697. Two subwoofers in opposite mode lobes can cancel room resonances without equalization — ch. 20
698. Seats placed on room-mode null lines increase seat-to-seat bass variation. — ch. 20
699. All subwoofers are equally fast at 80 Hz and rooms slow them down — ch. 20
700. Multiple subwoofers allow cheaper units at positions needing reduced drive — ch. 20
701. Seating that avoids low-order null lines reduces seat-to-seat variation — ch. 20
702. Multiple optimized subwoofers let a single global EQ filter flatten bass for every listener. — ch. 20
703. Multiple identical subwoofers reduce seat-to-seat bass variation — ch. 20
704. Knowing any two of room dimensions, subwoofer layout, and seating enables optimizing the third. — ch. 20
705. Slightly mis-tuned parametric filters still effectively attenuate targeted room modes — ch. 20
706. Mode cancellation neutralizes modes for the listening system but not the physical room — ch. 20
707. Rectangular rooms are favored because their modes are simply computable — ch. 20
708. Adding absorption reduces seat-to-seat bass variation significantly — ch. 20
709. Narrow-band tuned absorbers target specific modes while broadband traps address many — ch. 20
710. Room-acoustics research transfers poorly because listening rooms have known source and receiver positions. — ch. 20
711. Subwoofer placement conclusions were validated across many room dimensions. — ch. 20
712. Headphone sound preferences are remarkably consistent across countries and ages — ch. 21
713. Headphone preference tolerances are tightest in the speech-critical midrange. — ch. 21
714. Personalized HRTFs enable elevated externalized spatial audio over headphones — ch. 21
715. Listeners over 55 prefer brighter headphones, possibly from age-related hearing loss — ch. 21
716. Seal leakage makes closed-back headphone bass highly listener-dependent. — ch. 21
717. Listener segmentation analysis can predict headphone preference from demographics — ch. 21
718. Predicting preference is easier for in-ear than over-ear headphones — ch. 21
719. Ear simulator corrections depend on the headphone’s own acoustic load — ch. 21
720. No single headphone target satisfies most listeners — ch. 21
721. In-ear drum reference point measurements are rarely performed due to invasiveness and unreliability. — ch. 21
722. Noise-cancelling headphones now deliver up to 30 dB of isolation — ch. 21
723. Headphone frequency response varies across listeners by up to 9 dB. — ch. 21
724. Open-ear headphones lack bass and tempt users to raise volume against background noise — ch. 21
725. Headphones lack the phantom-center timbre notch because no interaural crosstalk exists. — ch. 21
726. Diffuse-field targets are least preferred, but adding bass improves them — ch. 21
727. Head-mounted measurement adds leakage absent from flat-plate fixtures — ch. 21
728. Test fixture fidelity to human measurements remains an open question — ch. 21
729. Headphone measurement variability is greatest below 500 Hz and above 3 kHz — ch. 21
730. Headphone sound quality depends on fit and acoustic seal around the ear — ch. 21
731. A flat steady-state in-room response boosts high-frequency direct sound — ch. 21
732. The open sound of open-back headphones may just be room acoustics leaking in. — ch. 21
733. Body and torso acoustics measurably shape the sound reaching the ears — ch. 21
734. Headphone listening increases agreement with and empathy for narrators — ch. 21
735. Tactile seat vibration substitutes for about 3 dB of headphone bass. — ch. 21
736. Pinna geometry alone changes headphone measurements through leakage — ch. 21
737. A headphone target curve descends gradually with frequency and boosts bass. — ch. 21
738. Headphone target measurement averages six manikin positions across three angles — ch. 21
739. Headphone bass boosts may compensate for missing haptic sensation from loudspeakers — ch. 21
740. Headphone measurements vary most between individuals at high frequencies. — ch. 21
741. Ear-tip insertion depth shifts canal resonance upward by several kilohertz — ch. 21
742. The preferred headphone EQ matches a 10 dB downward-sloped room response — ch. 21
743. Headphone preference ratings can be predicted from objective measurements like loudspeakers’ can. — ch. 21
744. DF headphone calibration avoids conflicting HRTF localization cues that make FF sound unnatural — ch. 21
745. Below-1 kHz resonances go unpunished by the prediction model despite lowering actual preference scores — ch. 21
746. Headphone reproduction lacks the spatial cues loudspeakers in rooms provide — ch. 21
747. Headphone sound preferences vary by gender, age, and listening experience — ch. 21
748. The rigorously validated Harman target became the industry’s blind-listening benchmark — ch. 21
749. Head and ear variation makes fixture measurements unreliable predictors of listening — ch. 21
750. Open-back headphones give consistent bass response across listeners because fit does not affect it. — ch. 21
751. Binaural room impulse responses generate spatial audio via convolution — ch. 21
752. Many daily headphone users disbelieve headphones cause hearing damage despite symptoms — ch. 21
753. Headphone retail price shows almost no correlation with sound quality — ch. 21
754. Headphone target curves can be derived computationally from HRTFs without a physical reference field. — ch. 21
755. Headphone bass perception varies with how well headphones seal on each ear — ch. 21
756. The flat DF target fails listening tests mainly due to insufficient bass — ch. 21
757. Headphone preference tests can be run virtually via equalization. — ch. 21
758. Artificial manikins can approximate a target population for headphone testing. — ch. 21
759. Headphones calibrated to semi-reflective room sound best reproduce stereo recordings made for loudspeakers. — ch. 21
760. Realistic noise reduction measures require soundscape recordings rather than pink noise. — ch. 21
761. ANC and PNC headphone performance is standardized as insertion loss measured with pink noise. — ch. 21
762. No single ear-simulator correction applies because error is headphone-specific — ch. 21
763. Headphones became the primary device through which entertainment is consumed — ch. 21
764. Top-rated headphone responses cluster tightly around a shared mean curve. — ch. 21
765. Open-back headphones deliver the most consistent response across listeners. — ch. 21
766. Test fixtures meeting the same standard still differ in headphone measurements. — ch. 21
767. Headphones are the most common device for experiencing spatial audio content — ch. 21
768. Subjective agreement requires identical delivered signals and matched objective measurements — ch. 21
769. A commercial reference target derives from flat near-field monitors — ch. 21
770. Leaks from hair, glasses, and jaw contours cause bass loss test fixtures miss — ch. 21
771. In-ear headphones produce the most 4 kHz hearing loss among headphone types — ch. 21
772. Physical headphone testing cannot be fully blinded because listeners feel weight and fit — ch. 21
773. Active noise cancellation reduces preferred listening volume, protecting hearing — ch. 21
774. Room reflections aid resonance audibility that headphones must control internally — ch. 21
775. Preference bounds, not a single target, statistically satisfy most headphone tastes — ch. 21
776. 3D-printed quintile heads let designers test headphones across a population distribution. — ch. 21
777. Binaural recordings capture nonlinear headphone distortions; virtual methods do not — ch. 21
778. Flat frequency targets suit binaural audio while Harman suits stereo — ch. 21
779. Twenty-dollar in-ear headphones can outperform costly loudspeakers in fidelity — ch. 21
780. Ear coupling and head size make headphone sound-quality opinions vary widely — ch. 21
781. Distinctly different headphone frequency responses can all be equally preferred — ch. 21
782. A shared loudspeaker and headphone target curve solves the Circle of Confusion — ch. 21
783. Audience bass preferences deviate from the Harman target by up to six dB. — ch. 21
784. Listeners strongly prefer the Harman target over DF, Lorho, and FF headphone targets — ch. 21
785. Listener-preferred headphone response mirrors a neutral loudspeaker’s in-room response — ch. 21
786. Headphone price poorly predicts predicted listener preference across all types — ch. 21
787. Headphone calibration shifted from subjective listeners to probe mics and HATS — ch. 21
788. The Harman in-ear target remains top-ranked across independent validation studies — ch. 21
789. Headphone preference tests used double-blind methods across a wide price range — ch. 21
790. The international standard DF target curve rates worse than alternatives — ch. 21
791. A five-target headphone preference test needed 350 listening trials — ch. 21
792. Coupler type 4.3 shifts both low and high frequency headphone readings — ch. 21
793. Preferred headphone tone adjustments depend on music program and listener attributes — ch. 21
794. Measurement accuracy on fixtures directly predicts agreement with human listeners — ch. 21
795. ANC headphones sound quality varies with noise environment and noise reduction performance. — ch. 21
796. Some listeners reject headphones due to in-head localization and lack of bass tactility — ch. 21
797. In-ear headphone performance data is scarce due to measurement challenges. — ch. 21
798. Modern insert headphones can limit output and measure hearing thresholds — ch. 22
799. Listener ‘clarity’ ratings correlate with intelligibility but are not a direct measure — ch. 22
800. For hearing-impaired viewers, unclear dialogue makes a movie unenjoyable — ch. 22
801. Inner-ear damage permanently corrupts higher-level auditory perception, not just thresholds — ch. 22
802. Loud movie mixes get turned down, dragging dialogue below intelligibility — ch. 22
803. Occupational noise limits fail to protect recreational hearing enjoyment — ch. 22
804. Ear protection alone does not fully prevent cumulative hearing damage — ch. 22
805. Cochlear damage produces distinct perceptual deficits depending on which cell type is affected — ch. 22
806. Inner ear hair cell damage accumulates before any measurable hearing threshold rise — ch. 22
807. Hearing-impaired listeners equate speech intelligibility with overall sound quality. — ch. 22
808. Repeated loud exposures convert temporary hearing loss into permanent damage — ch. 22
809. Mild hearing loss makes trained listeners give inconsistent sound quality judgments — ch. 22
810. Occupational noise standards accept measurable hearing loss and do not protect critical listening — ch. 22
811. Hearing impairment commonly begins between ages 30 and 44 — ch. 22
812. Custom musicians’ earplugs reduce volume without destroying timbre — ch. 22
813. Movie sound mixers understand dialogue partly because they have rehearsed it — ch. 22
814. A real center speaker improves dialogue clarity over a phantom center — ch. 22
815. Recreational gunfire is the most serious recreational threat to hearing — ch. 22
816. Chronic noise exposure causes tinnitus and hyperacusis even with hearing protection — ch. 22
817. Audiometrically normal listeners may still have substantial hidden hearing loss — ch. 22
818. Single-axis measurements misrepresent multidirectional loudspeakers like Bose — ch. 23
819. Sighted listening evaluations are biased regardless of listener expertise — ch. 23
820. Speaker break-in effects are listener adaptation, not hardware change — ch. 23
821. Bass rise in reflected sound is physically unavoidable with forward-firing speakers. — ch. 23
822. On-axis flatness alone fails without controlled off-axis directivity. — ch. 23
823. Loudspeakers and headphones dominate perceived reproduced sound quality — ch. 23
824. Modern loudspeakers have converged so far that choice among them is statistically a tie. — ch. 23
825. Listener preferences for neutral loudspeakers proved stable across decades and countries. — ch. 23
826. Resonance-free response and flat direct sound define timbral neutrality — ch. 23
827. Most loudspeakers need equalization to correct low-frequency room resonances — ch. 23
828. Blind listener tests reliably favor the most neutral loudspeakers — ch. 23
829. Flat on-axis response alone is insufficient; off-axis sound matters too. — ch. 23
830. The direct, on-axis sound dominates perceived loudspeaker quality in rooms. — ch. 23
831. Listeners largely agree on preference, and preferred speakers measure smoothest — ch. 23
832. Listeners can distinguish loudspeaker resonances from instrument resonances — ch. 23
833. Technical audio decisions need measurement science separate from artistic opinion — ch. 23
834. Beyond about 80 Hz, loudspeaker price governs aesthetics, output and distortion, not timbral accuracy. — ch. 23
835. Updating a classic loudspeaker can yield more output yet worse tonal quality. — ch. 23
836. Matching room curves via EQ does not equalize audible sound quality. — ch. 23
837. Highly regarded loudspeakers measured surprisingly ragged anechoic responses in the 1960s — ch. 23
838. Bass quality dominates overall sound satisfaction yet is room-controlled — ch. 23
839. Consumer loudspeakers at moderate prices rival professional monitors in sound quality. — ch. 23

Annotation Roundup

Question

• Anechoic-data equalization differs sharply from room calibration, which is often misused — What exactly separates anechoic-data speaker correction from room calibration? The mechanism of each is worth chasing in later chapters.
• Loudspeaker design targets are set by human listeners, not engineering metrics — What exactly does ‘graphical interpretation’ of performance targets mean methodologically — which graphs and which reading strategies?
• Silence intervals of half a second to a second aid auditory discrimination accuracy — How precisely does the 500 ms-1 s optimal interval relate to the cognitive persistence of a timbral identity? Worth chasing the Pike et al. (2014) details.
• Harmonic distortion measurements poorly predict audible annoyance from real music. — What alternative test signals or metrics (e.g., intermodulation distortion, noise-based probes) better predict audibility?
• Early blind loudspeaker comparison relied on single overall preference ratings — Contrast the single ‘gestalt’ 0-10 rating with today’s multidimensional listener-preference testing; a method-history note worth chasing.
• Musicians judge loudspeakers on different rationales and can be inconsistent raters. — What exactly is a ‘musically valid’ interpretation of an instrument sound and how does it diverge from a listener-preference judgment? Worth chasing the cited follow-up studies.
• Blind listening shows listeners consistently prefer flat, smooth anechoic frequency response — How did the adaptation-to-flawed-loudspeakers finding get quantified later? Worth chasing the habituation mechanism in later chapters.
• Low-frequency room resonances dominate how loudspeaker placement affects perceived quality. — What exactly is the 30% figure measuring — variance contribution, listener weighting, or something else? Worth chasing the original study.
• Oblique speaker placement pushes problem reflections into heavily attenuated off-axis angles — Author notes oblique placement is aesthetically unpopular—wonder about the exact tradeoff between aesthetic and acoustic priorities in real listening rooms.
• Recording monitors with deliberate response errors perpetuate the circle of confusion — Meyer 2009 figure 4.1 is cited for the microphone-above-violins brightness claim — worth chasing that source for the actual frequency data on string over-brightness.
• Crosstalk-cancelling filter technology has advanced with head tracking and multi-listener support. — Could chase down Bauck and Cooper (1996) and Choueiri (2010) references if a deep dive into crosstalk-cancellation filter design is warranted.
• ITU and EBU listening tests differ fundamentally as relative versus absolute judgments. — Worth investigating how this relative vs absolute distinction maps onto modern audio coding evaluation methods.
• Streaming loudness normalization is automating much of mastering engineering. — Worth chasing: which specific streaming loudness standards (e.g. LUFS targets) triggered the automation shift, and what measurable effect has automation had on master quality?
• A flawed consumer speaker became the recording industry’s standard near-field monitor. — What made the Auratone signature persist and get re-endorsed across decades despite objective flaws? Classic institutional persistence worth investigating.
• Cinema’s X-curve standard was based on primitive measurements that ignored better available research — What exactly was Ljungberg’s 1969 SMPTE guidance, and how did it differ from the X curve?
• Listeners perceptually normalize their own idiosyncratic HRTFs from birth — The chapter ends on ‘how flexible is that adaptation?’ — the plasticity limits of HRTF normalization remain an open research question worth chasing.
• Hearing adapts in real time to drastically modified HRTFs — This real-time adaptation mechanism — visual correlation and plausibility filtering — is a promising angle for why head-related transfer function corrections in headphones often underperform expectations.
• Perfect HRTF matching does not guarantee better headphone sound quality — The gap between theoretically perfect individualized HRTFs and real-world listener satisfaction is a live research puzzle — worth chasing the published evidence for adaptation over accuracy.
• Head movement resolves directional ambiguity and explains headphone sounds seeming internal — Toole cites his own 1970 work here; worth chasing whether later research quantified exactly how much head-tracking compensation improves externalization ratings.
• Matching acoustical and visual context yields convincing binaural externalization — How exactly does the visual context (sitting in the same stereo seat) gate the neural adaptation to binaural cues? Worth chasing the mechanism.
• Audio-video interactions grow stronger with channel count and screen size — How does screen size interact with a fixed loudspeaker layout — does the channel-count benefit plateau at a certain screen size?
• Loudspeaker directivity and early reflections affect sound quality and imaging — Which of the three directivity categories ultimately wins on listener preference, and does it overturn forum orthodoxy? Worth chasing across the chapter.
• Stereo presentation masks audible differences between loudspeakers found in mono. — The author never fully resolves why stereo masks these defects — is it masking, distraction, or something the stereo mix adds? Worth revisiting how the mechanisms interact.
• Reflected sound anchors external source localization while its absence pulls sound into the head — Worth chasing: what specific reflection timing and level thresholds prevent in-head localization in loudspeaker reproduction?
• Stereo’s dominance stemmed from LP storage limits, not audio ideals — Worth chasing how modern streaming removes the storage constraint yet stereo persists as the default.
• Live-versus-reproduced demos were contrived marketing that masked genuine loudspeaker flaws. — Worth chasing: whether contemporary high-end audio demos (showrooms, trade shows) still exploit the same contrived-settings effect today.
• Competing recordings of the same work show enormous, sometimes poor, perspective choices. — Which specific recordings or labels exemplify good vs bad auditory perspective choices? The claim invites a comparative listening study.
• Stereo phantom center images have a spectrum dip near 2 kHz from interaural crosstalk — Worth chasing: is this comb-filter dip the reason some listeners prefer true center-channel speakers even without loudspeaker placement constraints?
• The Schroeder frequency miscalculates for small furnished rooms but the transition is real — Worth tracing: what exactly accounts for the discrepancy between the computed 129 Hz and the visually observed transition, and does the 4000 vs 2000 constant resolve it.
• Timbral adaptation is a confirmed phenomenon though its mechanism remains unexplained — What precisely is the perceptual mechanism of timbral adaptation? Worth chasing the Watkins spectral compensation literature
• Room differences dominate loudspeaker differences when listeners cannot adapt — Does binaural measurement reveal normal room adaptation better than in-room monaural comparisons?
• Room size and shape do not change multiple-loudspeaker sound quality ratings — Does this result hold outside the controlled multi-loudspeaker method — or does room adaptation in real listening change ratings? The caveat is stated but the boundary is worth chasing.
• Listeners adapt to reverberant rooms within seconds, improving speech intelligibility by 18% — What are the ‘high-level perceptual processes’ that suppress acoustic reflections, and do they operate for music as well as speech?
• More playback channels increasingly mask audible loudspeaker resonances — Toole poses the mechanism question himself — why does more simultaneous resonance sources reduce audibility? Worth chasing the explanation later.
• Listeners prefer familiar distorted phantom images over technically superior real center channels — Worth chasing: does this preference generalize to other domains where perceptual habituation to distortion beats fidelity? This is a striking claim about preference formation.
• Bass performance drives roughly 30% of overall loudspeaker sound-quality ratings. — What specific limits on listener adaptation to resonant bass did the cited studies find? Worth chasing in Chapter 14 or the Olive 2004a/2004b papers.
• High-Q resonances are rarely heard but intensely annoying when triggered. — The claim that a measurement reveals such resonances immediately — but that the audibility depends on probability of excitation — raises the question of how measurement-driven design should weight high-Q resonances vs. low-Q ones.
• Recording complexity and reverberation raise the audible threshold for resonances — Why does program material (close-miked pop vs pink noise) raise resonance detection thresholds? Worth chasing the mechanism further.
• Multichannel reproduction progressively masks loudspeaker resonances except low-Q ones. — Why is a low-Q resonance (broad, gentle) the exception that remains audible rather than narrow high-Q ringers? Worth chasing the mechanism.
• Diffusor effectiveness in small listening rooms lacks subjective validation — Why has diffusion in small rooms gone so under-researched subjectively while mathematical modeling abounds? A gap worth chasing.
• Diffusing surfaces may not reduce perceived reflection loudness as expected — The Cremer and Müller perceptual-summation effect is referenced but not explained here — worth chasing what it actually is.
• ETC displays can misreport reflection levels by about 20 dB versus audibility — Worth chasing why the ETC inversion is so large (~20 dB) — is it energy integration band limits or time-windowing resolution?
• Acoustical materials alter reflection spectra, invalidating broadband measurements for audibility — What measurement alternatives do account for spectral differences between direct and reflected sound? This points toward a gap worth chasing in later chapters.
• Ceiling reflections are as detectable as lateral ones despite weak binaural cues — Interesting open puzzle: what monaural spectral mechanism allows vertical reflections to be as detectable as lateral ones that produce strong binaural cues?
• Phantom stereo images resist lateral-reflection interference as well as real images do — Whether phantom imaging remains robust under multiple simultaneous reflections or only under a single asymmetric one is worth chasing.
• The precedence effect fusion interval lengthens with signal continuity — Could chase down the Litovsky et al. 1999 source for the exact precedenteffect interval methodologies.
• Fibrous absorbers become ineffective below roughly a quarter-wavelength thickness. — The author flags that impulse measurement tends to reward high-frequency absorption visually — worth investigating how this biases practitioners’ choices of absorber thickness.
• Multichannel and immersive audio reduce the perceptual importance of small-room reflections. — Worth chasing: do recorded large-space sounds also mask aspects of the listening space, as the author explicitly raises?
• True envelopment needs reflections delayed beyond 80 ms, impossible in small rooms alone — Why 80 ms specifically? Worth checking whether this threshold maps to the precedence effect (Haas) or to the onset of perceived reverberance.
• Signal-adaptive matrix steering works only for single moving images — The single-image limitation of steering matrices is a concrete boundary condition worth contrasting with modern object-based audio rendering.
• Bass accounts for roughly 30 percent of perceived sound quality — Where does the 30% figure come from — is it a published rating study or Toole’s own listening-test data? Worth chasing down the source.
• Smaller rooms drastically worsen envelopment at off-center seats — Worth chasing: is 9.9 dB the point where side-speaker localization reliably dominates over envelopment across listeners, or does it vary?
• Opposite-wall reflections compensate for surround propagation loss at no cost — Worth verifying: is the claim that adding absorbers on the far wall would aggravate the lack of spaciousness a testable hypothesis in a real room?
• Listener-level channels, not height channels, drive spaciousness and envelopment — This is a strong, arguably contrarian claim about immersive audio — worth verifying against perceptual experiments on height-channel contributions to envelopment.
• Immersive systems could cheaply implement room reverb enhancement but none do. — Has any commercial immersive platform since this book’s writing shipped LARES-like room enhancement?
• Electroacoustic reverberation enhancement systems can invisibly reshape hall acoustics per performance. — How common are LARES-type installations in modern concert halls today?
• Immersive music masters have no stable target playback format. — What would a stable, future-proof immersive master even look like, if binaural rendering keeps changing?
• Receiver bass-management implementations vary, causing differing user experiences. — Whether a particular receiver discards or preserves the LFE band is often unadvertised, worth verifying before buying.
• Dolby’s 100 Hz Atmos crossover risks localizing subwoofers but is accepted for simplicity — Worth chasing: does a 100 Hz crossover actually produce audible subwoofer localization given front-wall placement, or is the risk mainly in theory?
• Car road noise exceeds music spectra below about 200 Hz — Worth chasing: Olive’s 1994 reference — which four programs, what content, and do modern pop/mastered-for-streaming spectra still hold that flat low-frequency shape?
• No accepted method rates subjective acceptability of ambient noise spectra — Worth chasing: has any newer metric (e.g., psychoacoustic annoyance models like Zwicker’s) filled this gap since 1985?
• Time and frequency resolution cannot both be improved simultaneously — The uncertainty principle tradeoff between frequency and time resolution in measurement — worth confirming the exact underlying math.
• A room appearing to ring at many frequencies actually has only one dominant resonance. — Curious how well psychoacoustic models predict audible salience of a resonance 10 dB down at onset versus closer-to-threshold resonances.
• No time-frequency analysis method has psychoacoustic validation for room decay. — Worth chasing: has any psychoacoustic study since this edition validated wavelet or Wigner-Ville displays against hearing?
• Half-wave rectification in the inner ear does not make polarity reversal audible — Toole leaves unresolved whether polarity reversals are audible and whether they matter — worth chasing the answer in later psychoacoustics literature.
• Group delay detection threshold is 1.6-2 ms — Worth chasing: what is the actual group delay produced by typical crossovers and box alignments, to see the margin between real design values and this threshold?
• Low-frequency phase shift accumulates massively across every stage of the signal chain — The author openly wonders if anyone has summed the total bass phase shift; a back-of-envelope accounting would be a nice quantitative follow-up.
• Audible acoustic polarity effects require the ear’s asymmetric detection process — Why no industry polarity standard exists, given it is demonstrably audible in select program material, seems worth chasing.
• Panel loudspeakers’ low-mass diaphragms do not actually respond faster than conventional coils — The claim that panel motors are weaker than coil motors is asserted without heavy quantitative support; worth verifying the motor-strength comparison.
• Diffuser depth sets a lower frequency below which no scattering occurs. — Worth chasing: the exact relationship between diffuser depth and transition frequency — is it a quarter-wavelength rule like absorbers?
• Equal-loudness contours are a fixed property of human hearing — The unresolved link between single-tone equal-loudness curves and complex music spectra is worth chasing into the literature.
• Room curve variations across control rooms distort recordings’ spectral balance — Worth chasing: how large are the low-frequency room curve variations across the 250 control rooms, and do engineers compensate perceptually for their own room?
• Listeners judge loudspeakers equally well on studio-produced popular music — Why exactly did listeners rate products better with studio-created music? The passage says the comments revealed ‘extravagant’ criticism of poor products.
• Stereo playback masks differences between loudspeakers with room reflections — The claim that recording-environment reflected-sound information ‘confuses the eye/ear perceptual system’ — I want the actual mechanism from Chapter 5 unpacked.
• Low-frequency performance drives roughly 30 percent of sound quality ratings — The 30% figure is a specific weighting worth chasing in earlier chapters for how it was derived from listening tests.
• Standard studio calibration levels are measurably too loud for typical listeners — A real gap: most published listening tests omit the playback level, making cross-study comparison of perceived quality results unreliable.
• Program material and recording quality strongly determine audibility of speaker defects — Which specific historical large-diaphragm microphones had such poor HF response? Worth chasing for concrete detail.
• Hi-fi enthusiasm predicts listening reliability better than musical training does — Why do hi-fi enthusiasts outperform trained musicians? Is it practice in critical A/B listening versus in-performance musical attention?
• Declared normal hearing can still hide degraded sound-quality opinions. — What specific hearing changes — high-frequency rolloffs, loudness recruitment — degrade sound-quality opinion before an audiogram flags them?
• Hearing-normal listeners give far more consistent loudspeaker quality ratings. — Why would low-frequency hearing thresholds specifically predict judgment variability rather than high-frequency loss? The broadband explanation suggested deserves follow-up.
• Hearing loss impairs spatial sound separation, not just frequency detection. — What mechanism links elevated thresholds to degraded spatial release from masking? Worth chasing down the binaural processing evidence.
• Averaged listener ratings can hide hearing-loss-driven individual disagreement — How does one detect and correct for high-variability listeners before averaging, and does this generalize beyond loudspeakers to any subjective rating data?
• Most loudspeaker reviews rely on sighted listening susceptible to bias — Why do so few publications adopt blind testing when the bias risk is documented? An institutional-incentive question worth pursuing.
• European multichannel loudness experiments matched listener judgments to model predictions. — The paragraph trails into ‘substantive conclusions were:’ that follow in 1183 only — worth tracking whether the detailed AES papers are worth chasing.
• Early loudspeaker preference studies were too crude to validate any measurement model — Worth chasing: does this ‘almost any measurement correlates’ problem still bias modern validation when equipment is uniformly poor?
• Fine-grained anechoic measurement statistics can near-perfectly predict listener preference rankings — Which specific spinorama statistics carried the predictive weight in Olive’s model? Worth tracing to the Olive 2004a/b papers.
• Home-room ‘reverberation time’ actually measures reflection or resonance decay — What distinguishes Reflection Decay Time from resonance ringing decay measurement in practice - how would an instrument classify which it is reading?
• The ITU-R BS.1116 standard is routinely misapplied to loudspeaker evaluation rooms. — Worth chasing: exactly how do ITU and IEC RT targets differ numerically, and what listening impairments does each guard against?
• Removing floor reflections makes sound unnatural to human listeners — What range of floor-reflection timing and spectral content does the brain treat as natural? Could relate to head-related transfer function experience.
• Minimizing floor-reflection dips in measured curves produced no audible improvement — Why do visible steady-state response artifacts from floor reflection fail to correlate with audibility? This seems like a core puzzle in psychoacoustics worth chasing.
• Floor reflections evolved as a constant cue for spatial judgment — Do floor-reflection cues underpin distance perception in ways that vary by terrain? Worth chasing the evolutionary-acoustics literature.
• On-axis frequency response cannot predict in-room measurements but does predict perceived sound. — Why does sound power matter progressively less with rising frequency (referenced from Figure 2.6(d))? Worth tracing the underlying psychoacoustic reasoning for ear-directional high-frequency hearing.
• Above 500 Hz room curves are predictable from anechoic loudspeaker data — Worth chasing: the 4-vs-109 microphone agreement in a cinema suggests heavy spatial averaging may be overkill at mid/high frequencies — a useful practical takeaway for measurement methodology.
• Untrained listeners in method-of-adjustment tests prefer the boosted “happy face” spectrum. — The open question — why do untrained listeners over-boost in method-of-adjustment yet rate neutral speakers higher in blind comparisons? — points to the difference between preference-with-controls and preference-for-sound.
• Room treatment absorbers receive sound at 45 to 60 degrees incidence — Why has directional absorption only recently been studied — what method made it tractable? Worth chasing the literature.
• Most commercial diffusers are designed for looks rather than measurable acoustic performance — Which diffuser designs actually publish meaningful specs? Worth chasing a benchmark source (Cox & D’Antonio is cited).
• Multiple subwoofers can replace bass traps and even improve efficiency — Chapter 14 is referenced as the payoff — worth checking to see how sub arrays increase rather than decrease system efficiency.
• Binaural and crosstalk-cancelled delivery may finally make multichannel practical — Worth chasing: current state and maturity of crosstalk-cancelled two-loudspeaker and headphone binaural formats as of this edition — has this prediction borne out?
• Early reflections within 30-40 ms improve speech intelligibility — How does this early reflection benefit differ between speech and music, or between listeners using binaural hearing aids?
• Mini-reflections perceptually add up beyond what visual reflection analysis predicts — The claim that diffuse mini-reflections perceptually sum beyond ETC predictions suggests perceptual integration rules psychoacousticians haven’t fully mapped yet.
• Sighted evaluations of acoustical rooms are biased by visual distinctiveness — Binaural double-blind room comparisons would settle whether visual distinctiveness is driving favorable evaluations.
• Listeners must sit at least three wavelengths from diffusers to avoid coloration — The chapter itself asks whether listeners actually notice the coloration from too-close diffusers — worth chasing the research.
• Curved, Legendre-shaded line arrays exploit floor reflections to maintain constant beamwidth at all frequencies — Why does a Hann shading contour (1290) not deliver the constant directivity that the Legendre contour achieves on the curved line — what is the psychoacoustic/cx design logic behind the specific contour choice?
• Boundary placement boosts low-frequency output by 6 dB per solid-angle halving. — Worth chasing: the exact interaction described — rear-face reflection arriving back at the diaphragm — is a specific mechanism that could generalize to other driver/enclosure geometries.
• Spatial averaging and in-situ power measurement reveal identical boundary effects — Worth chasing: how does spatial averaging differ in cost and reliability from in-situ power measurement across varying room sizes?
• Smaller drivers radiate more omnidirectionally at a wider frequency range — What is the exact driver-size-to-wavefront relationship that sets where a driver transitions from omnidirectional to directional?
• Comparative measurements remain reliable even without absolute low-frequency accuracy — How much does a non-perfectly-anechoic chamber and a wall structure compromise low-frequency absolute accuracy, and what magnitude of error is considered acceptable?
• Opposing in-phase subwoofers cancel odd-order axial modes but amplify even-order ones. — Worth chasing: why do second-order mode pressure nulls sit at 25% and 75% between walls, and how that exact geometry protects a central listening area.
• Double bass arrays keep high efficiency despite half the units cancelling — Counterintuitive that deliberately cancelling half the array’s output doesn’t seriously hurt efficiency — worth understanding the mechanism behind the peaks-and-dips minimization.
• Resonant peaks bother more listeners than nulls because they occupy most of the room — Worth chasing: how exactly does psychoacoustic masking make excess sound worse than deficit in modal contexts? The section reference suggests a known asymmetry.
• Slightly mis-tuned parametric filters still effectively attenuate targeted room modes — How robust are modal filters to Q mismatch in practice? This hints at a forgiveness margin worth quantifying.
• Higher-Q resonances become less audible because music rarely energizes them — How does this 3 dB per Q-doubling rule compare to the low-frequency (below 200 Hz) region where resonant modal behavior differs from the diffuse-field region?
• Adding extra subwoofers rarely improves bass without controlled placement — Opens the practical question of the concrete placement rules that make multi-sub setups work.
• Spatial low bass below 50-63 Hz has an audible directional cutoff — The chapter admits no definitive experiments exist yet on delivering low-bass spatial cues — worth tracking as open research.
• Room pressurization is a compliance effect that fades in unsealed rooms — What is the practical magnitude of the unsealed-room loss, and does door/window leakage meaningfully defeat pressurization?
• Respected researchers disagree on optimal room ratios, undermining confidence in the concept. — What exactly are the differing optimal ratios each researcher arrived at? Worth chasing the Bolt, Louden, etc. numbers.
• Headphone frequency response varies across listeners by up to 9 dB. — Which headphone models and measurement fixtures were used, and does the 1-3 kHz anomaly trace to a specific design cause?
• ANC and PNC headphone performance is standardized as insertion loss measured with pink noise. — Worth chasing the actual 60628-24 standard’s exact pass/fail criteria and how insertion loss in phons is computed.
• Headphone target curves can be derived computationally from HRTFs without a physical reference field. — How exactly is the blocked ear canal HRTF measured, and how does ‘blocked’ differ from other measurement points (eardrum, open canal)? Worth pinning down for the measurement chapter.
• Listeners strongly prefer the Harman target over DF, Lorho, and FF headphone targets — The specific spectral-correction relation — why 2-4kHz emphasis/hollowness feedback maps to high-energy listeners’ descriptions — invites exploration of the perceptual basis for upper-midrange spectral sensitivity.
• Listeners over 55 prefer brighter headphones, possibly from age-related hearing loss — Whether age-related high-frequency hearing loss specifically drives spectral preference changes in headphone target curves is left open and worth investigating.
• Headphone sound preferences vary by gender, age, and listening experience — Why do older listeners prefer MORE treble when age-related hearing loss (presbycusis) typically attenuates high frequencies? Is this a compensation mechanism or something else?
• Headphone sound preferences vary by gender, age, and listening experience — The hearing-loss-as-confounder hypothesis for the over-50, less-bass class deserves chasing — is an aging high-frequency loss actually measured, or just inferred from age?
• Distinctly different headphone frequency responses can all be equally preferred — Why would women rate the Low Bass target higher yet prefer less bass in other studies? Is the Low Bass anchor disliked less by women because bass-heavy targets reinforce a male-idolized sound signature, or something neurological?
• Headphone preference tolerances are tightest in the speech-critical midrange. — The broadest tolerance (±3.5 dB at 3-5 kHz) sits right in a highly audible region — worth chasing whether listeners are simply least sensitive there or whether individual taste diverges most there.
• Top-rated headphone responses cluster tightly around a shared mean curve. — A methodological detail: a third-party Harman target wasn’t fixture-translated, yet top rated headphones still clustered near it — is the translation requirement smaller than thought?
• Flat frequency targets suit binaural audio while Harman suits stereo — Why does the preferred target shift with content type — is it about spectral cues that binaural rendering already provides?
• Headphone bass boosts may compensate for missing haptic sensation from loudspeakers — The 3 dB haptic-info compensation claim is intriguing — is there a measured basis or is it heuristic?
• The international standard DF target curve rates worse than alternatives — Which exactly is DF target 521 and does it differ from 514 and 713 in documented perceptual underpinnings?
• Headphone listening increases agreement with and empathy for narrators — Is the heightened agreement driven by the intimacy/lack of distance, or by reduced external interference? The mechanism is only statistically inferred here.
• Headphones became the primary device through which entertainment is consumed — The 60% in-home figure is striking — what drives a loudspeaker/room person to take this seriously? Worth chasing the Bull and Duvall source.
• Noise-cancelling headphones now deliver up to 30 dB of isolation — Is that 30 dB an active cancellation figure at specific frequencies, or total isolation? Context matters for comparison to passive attenuation claims.
• Open-back headphones give consistent bass response across listeners because fit does not affect it. — Best response consistency across listeners is precisely what psychoacoustic experiments need; worth chasing the fit-seal literature further given the reading purpose.
• The open sound of open-back headphones may just be room acoustics leaking in. — Is there psychoacoustic evidence the spaciousness of open-backs is really just room leakage? Worth investigating for the hearing-audio-application goal.
• Open-ear headphones lack bass and tempt users to raise volume against background noise — The author raises but doesn’t resolve whether certain headphone types promote hearing loss — worth following whether later chapters address this.
• In-ear headphones produce the most 4 kHz hearing loss among headphone types — The finding that open-ear designs caused 3.9 dB loss but semi-open only 0.1 dB is odd — the ordering doesn’t obviously track acoustic isolation. Worth checking the original paper for what ‘semi-open’ means in their sample sizing.
• Body and torso acoustics measurably shape the sound reaching the ears — These body-interaction effects (5 dB notch, 20 dB shadow) are why torso-less headphone-only fixtures diverge from real listening — worth chasing how headphone makers weigh this.
• Inner-ear damage permanently corrupts higher-level auditory perception, not just thresholds — Which higher-level perceptual aspects in the brain are modified, and how are they measured beyond threshold audiometry? Worth chasing into Moore (2016).
• Modern insert headphones can limit output and measure hearing thresholds — The author flags hearing threshold measurements via headphones as ‘accuracy to be confirmed’—worth chasing what validation exists.
• Inner ear hair cell damage accumulates before any measurable hearing threshold rise — The sub-threshold damage mechanism — hair cell loss below audiometric detection — is worth chasing to understand the gap between psychoacoustic test results and reported listening experience.
• Hearing impairment commonly begins between ages 30 and 44 — Worth chasing: how much of the early onset is occupational/recreational noise exposure versus age-related inner-ear changes, and does the same cohort show it in standard audiograms or only in this speech task?
• Occupational noise limits fail to protect recreational hearing enjoyment — Worth chasing: what are the actual official occupational noise exposure limits and their dB thresholds versus the levels needed to preserve near-normal high-frequency hearing?
• Listeners can distinguish loudspeaker resonances from instrument resonances — What acoustic/psychoacoustic cues let the ear separate loudspeaker resonances from instrument resonances within the same reflected field? Worth chasing for the mechanism. Xref
• Listeners rate neutral, uncolored reproduction as best, preferring it to any coloration. — Directly prepares the reader for the psychoacoustic ideal of transparency in reproduced sound; connects to how ‘least bad’ aligns with the book’s later treatment of colorations and timbral errors.
• Human sound-quality judgments are skewed by expectation biases, not just the sound itself. — Connects to decades of blind-testing methodology in audio and to the placebo effect literature in medicine; also echo of how expert judgment is unreliable in other perception domains.
• Loudspeaker design targets are set by human listeners, not engineering metrics — Connects to Toole’s core theme in this book that subjective listener response, not measurements alone, defines loudspeaker quality — his ‘spinorama’ and preference-rating work.
• Blind-tested listeners with normal hearing produce reliable, measurement-grade subjective ratings — Connects to listener-training and loudness-matching research in psychoacoustics and to the reliability of expert panels generally.
• Sighted loudspeaker evaluations are contaminated by non-auditory visual and social cues — Connects to the sighted vs blind-test methodology debates common in audiophile discourse and to placebo effects in perception more broadly.
• Reliable subjective ratings are prerequisites for validating technical measurements — Points forward to the blind-testing methodology Toole develops throughout the book; also connects to general claims about measurement validity requiring ground truth.
• Instantaneous switching between looped program excerpts yields more revealing audio evaluations. — Directly relevant to loudspeaker review methodology in Stereophile / SoundStage tests and how they structure A/B comparisons.
• Paired comparisons demand six times more trials than multiple comparisons for four loudspeakers. — Connects to experimental-design tradeoffs in other sensory-evaluation fields (wine tasting, food A/B testing).
• Comparing two sound samples requires accurate auditory memory of a timbral identity. — Auditory memory limits here echo similar short-term memory windows in visual discrimination and musical performance training literature.
• Parametric equalization of minimum-phase resonances also reduces time-domain ringing — Connects to the well-known concept in digital audio DSP that simple EQ can fix ringing in min-phase resonators — echoes the ‘phase is linked to magnitude’ insight familiar from IIR filter design.
• Harmonic distortion measurements poorly predict audible annoyance from real music. — Directly connects to the perception of masking literature; single-tone tests are unrepresentative because broadband signals mask distortion products.
• Panel movement alone does not indicate audibly radiated sound. — Connects to the general physics principle that net acoustic radiation depends on phase relationships across a surface, as in dipole vs monopole cancellation.
• Equal-level stereo speakers create a phantom image midway between them — This is the soundstage analogue of the reader’s grafting piece: compatibility between matched units matters more than the absolute quality of each — parallel to how grafted trees depend on the union, not each rootstock.
• Phase response stops being audible once sound leaves the loudspeaker — Connects to the reader’s earlier work on trees as infrastructure in that both concern what matters only in context — structure that is load-bearing at one scale and irrelevant at another.
• Room reflections are essential; anechoic listening is deeply unpleasant — Connects to the reader’s prior work on quiet places and silence — the anechoic chamber appears in One Square Inch of Silence as a disorienting, unpleasant space, directly confirming this claim.
• Microphone choice in recordings biases subjective loudspeaker ratings — Relates directly to the ADDENDUM article ‘On Sacrifice’? No — rather connects to general circularity/self-reference problems found in calibration loops and validation of instruments elsewhere.
• Double-blind evaluation can identify the most transparent loudspeakers — Connects to the book’s core thesis that subjective preference and technical measurement converge under blind listening conditions.
• Early binaural headphone studies localized sounds inside the head rather than externally. — This is the foundational in-head vs externalized localization distinction that the book’s later chapters on loudspeakers and rooms will develop.
• British engineering schools restricted colonial students from popular courses even with acceptance letters. — Historical detail on colonial exclusion connects to broader empire/postcolonial literature the reader keeps (e.g. Naqvi’s Home Boy’s immigrant experience).
• Signal synthesis enabled creative experimental tests of hearing. — Technical recall for this claimant (given that Dr. Cherry was his professor).
• Signal synthesis enabled creative experimental tests of hearing. — Technical skill enabling experimental innovation parallels how the reader’s own engineering background might inform psychoacoustic method.
• Blind listeners largely agreed on loudspeaker preferences, matching measurement quality — Connects to the book’s own later chapters on the correlation between flat anechoic response and preference; also to general literature showing listener consensus in controlled blind tests.
• Musicians judge loudspeakers on different rationales and can be inconsistent raters. — Connects to listener-education debates in audio reviewing and blind-testing methodology, and to the golden-eared-audiophile literature on expert listeners.
• Smooth flat on- and off-axis response correlates with subjective preference. — Foreshadows the book’s central thesis that measured smoothness predicts subjective preference — the same claim later formalized in Spinorama and CEA-2034 work.
• Different loudspeaker topologies each produce characteristic on- and off-axis flaws. — The observation that ESL panels hurt off-axis response foreshadows the modern directivity-dispersion tradeoff discussion central to loudspeaker design.
• Early listening tests required repeated short passages heard through every loudspeaker. — Methodological lesson about controlled A/B testing that parallels ABX testing and audio reviewing practice today.
• Blind listening shows listeners consistently prefer flat, smooth anechoic frequency response — Contradicts the ‘we all hear differently’ claim that later chapters dismantle with preference studies; supports the measured-to-heard mapping thesis of the whole book.
• No scientific evidence shows audible break-in changes except minor woofer low-bass compliance — Echoes the reader’s interest in causal mechanisms: a physical mechanism (suspension compliance) explains the only real break-in effect.
• Single-stimulus listening relies on capricious long-term memory and yields contradictory opinions — Connects to the method-criticism thread in the soundscape/silence books about how measurement context shapes judgment — and to the Milgrom material on how evaluation depends on comparison information.
• Low-frequency room resonances dominate how loudspeaker placement affects perceived quality. — Directly relevant to the reader’s audio/coding work: room modes dominate quality assessment below 300-500 Hz.
• Subjective listening tests require repetition and randomization to be statistically valid — Core methodology behind double-blind audio evaluation, foundational to psychoacoustic testing standards.
• Relaxed room-standard requirements eroded the comparability that motivated them — Parallel to standards-capture dynamics: standards loosened to accommodate existing certified rooms, defeating their purpose.
• Randomizing positions and identifiers cancels room standing-wave biases in double-blind tests — The randomization of listener/loudspeaker positions to defeat room modes is a clever experimental technique worth emulating.
• The LP medium was fundamentally incapable of reproducing master tape sound — This grounds the later, larger point that LPs were the weak link in the audio chain, setting up why digital source material became essential for controlled listening tests.
• Canadian audio magazines contributed test products and journalists to NRCC blind listening tests — Connects to the broader research-methodology thread of how double-blind protocols were applied to loudspeaker review, and to the business-of-hi-fi tension between advertisers and honest reviews.
• Room acoustics were the one loudspeaker variable manufacturers could not control without EQ — Connects to how modern room correction systems (Audyssey, Dirac, ARC Genesis) descend from this research lineage.
• Industry rivals codified Harman’s research into a formal loudspeaker measurement standard — Connects to the broader theme of how contested measurement standards get institutionalized—echoes the Milgrom/Shapiro material on institutions formalizing informal practices.
• Sound Field Management handles flexible subwoofer placement in irregular room shapes — Sound Field Management resembles adaptive array-processing and optimization approaches from other signal-processing domains.
• Historical loudspeaker measurements were non-standardized and largely kept from the public — Connects to the broader history of audio measurement standardization and subjective review culture; relates to themes in the reader’s psychoacoustics reading on how specifications mislead consumers.
• Published spinorama measurements frequently violate standard resolution requirements and are then unreliable — Connects to the earlier chapter’s discussion of Klippel near-field scanning as the measurement method behind modern spinorama data.
• Matched room curves do not guarantee matching direct sound for imaging — Connects to the reader’s noise/silence work on how perceived sound differs from measured ambient levels - here, steady-state measurements hiding the perceptually dominant direct sound.
• Room curves are measurement results, not equalization targets, except at bass — Connects to room equalization debates and the ‘cocktail party’ of target curves in modern digital room correction tools like Dirac and Audyssey.
• Audiophile press acclaim and high prices do not reliably predict speakers’ blind-tested performance rankings. — Echoes the broader ‘expert judgment fails blind testing’ pattern found across wine, music gear, and other experience goods markets.
• Recording monitors with deliberate response errors perpetuate the circle of confusion — Connects to the ‘circle of confusion’ concept of loudspeaker-to-recording compatibility; relevant to the reader’s interest in how physical stimuli cause perceptual outcomes in recording practice.
• Perceptual masking hides large LP distortions that measurements reveal — Central theme of the reader’s entire psychoacoustics project — masking as the mechanism by which objectively poor transducers sound subjectively acceptable.
• Record label tape-erasure practices corrupted early CD releases at the source — Connects to the ‘parental/market choice format war’ thread — a format-battle data point where the presumption of source superiority is false.
• Bass accounts for roughly 30 percent of perceived sound quality — Connects to room acoustics and bass management topics in audio engineering, and to the standing interest in psychoacoustic models of overall quality.
• Professional monitors rated lower than consumer products in blind sound quality tests. — Connects to the book’s earlier chapters on listening tests and blind evaluations, and to the general finding that habituation biases subjective preference.
• Measurement axes produce low-frequency calibration errors from woofer offset and port placement — Connects to earlier chamber calibration and standing-wave material in this chapter/previous chapters on measuring loudspeakers in rooms.
• Bass accounts for roughly 30 percent of perceived sound quality — Direct, quantitative anchor for the reader’s stated goal of connecting psychoacoustic models to real loudspeaker application — bass contributes a specific weighted share of overall quality judgments.
• Listener preferences correlate visually with smooth, flat anechoic on- and off-axis response. — Supports the reader’s core aim: linking anechoic measurement data to perceptual outcomes, which is the foundation of the loudspeaker measurement standard this chapter introduces.
• Listener perception depends on sound power, direct sound, and reflections by frequency band — Connects to the standing directive claim about small acts of decorum — here it’s the analogous insight that multiple partial measures, not one idealized curve, constitute fidelity to the listening experience.
• Spinorama measurement grew out of loudspeaker-room interaction studies — Connects to modern loudspeaker reviews that publish spinorama plots; clarifies the historical derivation of that standard format.
• Virtualized loudspeaker playback can compete with real multi-speaker systems on listener preference. — Connects to the reader’s stated interest in psychoacoustic models applied to real products; also echoes the earlier theme from One Square Inch of Silence that absence/attenuation of the source can heighten perception of the recording itself.
• Mixing decisions are monitored through loudspeakers in a room. — Establishes that the room and loudspeaker used for monitoring shape the final artistic result—ties to the book’s room-acoustics themes.
• Professional control room designs range from dead to highly diffuse. — The ‘non-room’ vs ‘live-end dead-end’ spectruum connects to domestic listening room treatment debates.
• Home recording democratization raises demand for quality monitoring in untreated rooms. — Set up for the central theme of the book: loudspeaker and room interactions matter.
• Most US music is now produced in residential, acoustically poor rooms — Connects to why room correction and accurate loudspeakers matter: the domestic listening-room chain now includes production, so translation failures accumulate.
• Control-room design choices rest on preference, not validated science — This mirrors the book’s persistent argument that audio design choices often lack double-blind subjective testing—the same theme Toole applies to loudspeaker evaluation throughout.
• Mixing in acoustically dead rooms complicates translation to lively home listening — The translation problem connects to the book’s broader theme of reconciling room acoustics with loudspeaker neutrality and to the earlier discussion of the listening room’s influence.
• Acoustically acceptable rooms require neutral loudspeakers plus acoustical treatment — Directly ties to the book’s central precept that neutral loudspeakers are the starting point before room treatment, a theme threaded throughout all chapters.
• Recording engineers preferred direct-sound fields partly to mask poor monitor loudspeakers. — Connects to ‘Grafting & Growth’ only loosely; better connects to the general theme that technical standards often encode contingent historical accidents — similar to how Milgrom’s law-merchant institutions encoded particular constraints.
• A flawed consumer speaker became the recording industry’s standard near-field monitor. — Connects to the reader’s psychoacoustics goal: ‘expert listening’ often runs on arbitrary anchors — recalls how mastering engineers later learn to compensate for known bad monitors.
• Cinema’s non-neutral spectral target forces engineers to compensate and varies across venues — Connects to the circle of confusion concept from Figure 1.8 and Chapter 1 of this book.
• In-room measurement curves are dominated by reflections, not direct sound — Connects to the room acoustics and loudspeaker directivity measurement discussions likely in earlier chapters of this same book.
• Microphone choice in recordings biases subjective loudspeaker ratings — Rebuilds the chapter 1 ‘circle of confusion’ point: every link in the chain colors subjective judgment.
• Point-source mic capture loses the binaural ability to separate direct from reflected sound — Connects to the psychoacoustic mechanism of binaural hearing commonly covered in Toole’s companion acoustic research and to precedence/HAAS effect discussions.
• Home and headphone listening lacks the scientific research its prevalence warrants — Connects to Samuel Butler-cite folklore-over-science themes and to how unregulated domains get governed by fashion—echoes the reader’s noise/soundscape books where marginal acoustic spaces are under-researched.
• Unidentified or invisible sounds are perceived as coming from behind the head — Connects to the evolutionary/defense-mechanism framing of sound localization used in Hupatz/Schafer’s work on signal versus noise in the soundscape.
• Matching acoustical and visual context yields convincing binaural externalization — Connects to the earlier chapter and reader’s interest in how physical stimuli produce perceptual responses; the acoustic-visual context matching mechanism underpins why binaural reproduction usually fails.
• Matching acoustical and visual context yields convincing binaural externalization — Directly corroborates the mechanism observed in the Sennheiser anecdote (296): acoustical-context matching drives externalization more than HRTF accuracy alone.
• Listeners adapt within minutes to externalize sound even through crude transducer devices — Echoes the adaptation mechanism in the Sennheiser anecdote (296) and reinforces that neural plasticity, not transducer fidelity, drives externalization.
• Binaural audio without visuals and head tracking stays internalized in the head — Directly connects with the reader’s psychoacoustics interest in externalization cues and head-tracking in modern binaural listening products.
• Crosstalk cancellation delivers binaural separation through loudspeakers — Core topic in the reader’s loudspeaker/room psychoacoustics interest — sweet-spot dependence of crosstalk-cancelled spatial audio.
• Audio-video interactions grow stronger with channel count and screen size — Connects to the reader’s interest in how multimodal cues shape perceived spatial realism in reproduction systems.
• Individualized HRTF data is required for reliable crosstalk cancellation — Connects to the reader’s stated pursuit of psychoacoustic models of spatial hearing and loudspeaker reproduction.
• Binaural hearing separates direct and reflected sound while monaural microphones cannot — Connects to binaural/betty hearing cues established earlier in the book and to conventional wisdom about close-mic multi-mic recording technique.
• Toe-in loudspeaker aiming failed to stabilize phantom center imagery off-axis — Connects to time/intensity trading (a core psychoacoustic principle) and its dependence on signal spectral and temporal structure.
• Fully steerable loudspeaker arrays are technically feasible but priced out of existence — Connects to modern beamforming loudspeaker and soundbar technology, which partially realized this steerable-array vision.
• High broadband directivity reduces lateral reflection levels in loudspeakers — Connects to the reader’s ongoing interest in loudspeaker directivity and its room-interaction consequences from Rooms chapters.
• Room reflections mitigate the phantom-center comb-filter dip near 2 kHz. — Parallel to the concert-hall seat-dip effect; this is a strong psychoacoustic illustration of why measured artifacts ≠ perceptual defects, central to the reader’s model-building interest.
• Stereo presentation masks audible differences between loudspeakers found in mono. — Connects to the earlier discussion in this same chapter about phantom center imaging and the 2 kHz dip; also parallels visual masking/superiority effects in perception.
• Early lateral reflections are not necessarily audible problems in stereo listening — Extends the standing-debate in acoustic design about lateral reflections vs. the auditory precedence effect; connects to Toole’s broader thesis that measured specular reflection is not perceptual defect.
• Wide-dispersion loudspeakers with room reflections create a you-are-there listening perspective — Connects to interaural cross correlation (IACC) and apparent source width concepts that predict envelopment, linking loudspeaker directivity to spatial perception.
• Room reflection effects are masked by spatial information already in recordings — Relevant to choice of recording technique (Blumlein pair vs. multimic) and how much of perceived spatial quality comes from the recording vs. the room.
• Listeners perceive the larger of two superimposed spaces in sound reproduction. — Connects to precedence effect and binaural psychoacoustics of spatial dominance; also echoes the ‘sound bubble’ concept in immersive audio.
• Early recording technology forced performers and dead-acoustic studios as standard practice — Connects to complaints about ‘immodesty’ article’s theme of technological constraints shaping cultural practice — here the recording medium’s insensitivity shaped musical performance norms like vibrato suppression and close miking.
• Accurate soundstage alone cannot satisfy musically without reproduced hall reflections — Directly relevant to the reader’s existing DEEPTHINKING material on envelopment vs. reverberation time; reinforces the distinction between soundstage and envelopment as separate perceptual dimensions.
• Stereo’s dominance stemmed from LP storage limits, not audio ideals — Technology-limited format choices echo how vinyl’s groove constraints shaped musical performance width, related to the milgrom trade-institution theme of physical constraints determining practice.
• Stereo principles were understood by 1931 but waited decades for commercialization. — The delayed-adoption pattern of stereo echoes the copyright-holders’ resistance described in The Library regarding print technology adoption.
• Music industry resisted multichannel audio for cost reasons at every stage — Parallels the industry cost-resistance pattern seen in early print vs manuscript economics.
• Hall reverberation cloaks loudspeaker defects in live-versus-reproduced demonstrations — The ‘circle of confusion’ concept ties directly into the channel’s existing audio/soundscape reading; hall reverberation cloaking reproduced sound parallels how ambient sound in general shapes perceived quality.
• Stereo phantom images timbrally differ from real-source or mono center images. — Connects to the phantom-image timbre-vs-localization tradeoff debates in multi-channel upmix and center-channel design, relevant to Toole’s broader room/loudspeaker arguments.
• Direct-sound-dominated rooms maximize the stereo center-image spectral distortion — Ties to the debate between reflection-controlled vs. reflective rooms that runs through loudspeaker room-acoustics literature (e.g., Toole’s own prior work).
• Room reflections partially fill the phantom-center spectral hole — Directly complicates the anechoic/near-field scenario from the preceding paragraphs; a nice intra-chapter dialectic.
• Steady-state room curves above 400-500 Hz misrepresent perceived sound quality. — Echoes the book’s earlier point about binaural hearing versus omnidirectional microphones (Figure 1.5) — the reason single-point measurements cannot stand in for two-eared perception.
• Rooms shift absolute ratings but not loudspeaker rankings in multiple-loudspeaker comparisons — Connects to the reader’s earlier notes on experimental listening-test methodology and how rooms shape perception; also relevant to audio evaluation practice.
• Gently rising bass response is both natural and preferred in loudspeakers — Connects to earlier chapter 3/5 material on steady-state room curves and loudspeaker voicing targets.
• Program material choice determines which loudspeaker or room flaws get revealed — Mirrors the signal-vs-noise problem from psychoacoustics: which input features of a stimulus excite which detector/receptor populations.
• Room differences dominate loudspeaker differences when listeners cannot adapt — Connects to the well-documented ‘headphone vs loudspeaker’ measurement paradox and room-normalization research in Toole’s earlier chapters and Olive’s work.
• Room resonance excess masks loudspeaker bass deficiency to listeners — Echoes the phantom-bass and room-gain phenomena from earlier chapters; also the ‘bass is rewarded’ finding connects to why boosted low end sells consumer speakers.
• Early room reflections benefit speech intelligibility as much as raised direct sound level — This overturns the instinct that room reflections are only a problem; relates to the book’s broader ‘listeners adapt to rooms’ argument.
• Normal listening rooms improve rather than impair speech intelligibility — Contrasts with the common audiophile premise that room reflections are always enemies to be damped away.
• More playback channels increasingly mask audible loudspeaker resonances — Links to the reader’s stated goal of understanding how physical stimuli cause perceptual responses; this is a core masking phenomenon.
• Home theater center channels are often inferior despite being the most important speaker — Relates to the reader’s interest in why engineering decisions get distorted by marketing in audio equipment markets.
• The hearing system adapts well to phantom stereo images despite conflicting HRTF cues — Connects to the reader’s psychoacoustics grounding in HRTF localisation cues and how the auditory system resolves conflicting spatial information.
• Car cabins create unique acoustics with no ideal listening position. — Connects to the reader’s existing understanding of listening rooms as infrastructure — the car cabin is an extreme case of ‘room as unwanted acoustic container’.
• Listeners are forgiving of headphone resonances but sensitive to bass-level air leaks. — Ties to the broader theme that direct sound dominates quality perception; connects to Chapter 15 on headphone targets.
• Listeners perceptually normalize voices across changing room acoustics via direct sound and visual cues — Connects to psychoacoustic precedence effect and room-acoustics perception; resonates with Haas effect literature and with adaptive normalization in vision.
• Speech and solo instruments reveal loudspeaker flaws least, dense broadband music most — Connects to the reader’s interest in practical psychoacoustic application — choosing test signals that stress a system’s weak points.
• Room reflections improve the ear’s ability to hear resonances in playback. — Connects to the reader’s broader interest in psychoacoustic models — this is about how the listening environment shapes what the ear can detect, relevant to both headphone and room-based reproduction.
• Above 200 Hz the spectral peak, not the ringing, determines resonance audibility. — Pays off the earlier claim that specs should be measured anechoically; also a foundation for headphone evaluation criteria discussed in Chapter 15.
• Tone-control adjustments are easily heard because low-Q resonance thresholds are tiny — Explains listener audibility of EQ and tone-control steps — connects to the perceptual side of whether ±3 dB speaker specs matter.
• Frequency response tolerances are meaningless without specifying the bandwidth of deviations — Resonance bandwidth (Q) governs audibility — the same Q-dependent audibility theme running throughout this chapter.
• More playback channels increasingly mask audible loudspeaker resonances — Connects to how increased channel count/signal complexity reduces perceptual discernment — parallel to cocktail-party and masking phenomena in psychoacoustics.
• Low-frequency room resonances dominate how loudspeaker placement affects perceived quality. — Links to the standing claim that low-frequency modal behavior — not mid/high — is the dominant room influence on sound quality, reinforcing room-correction priorities.
• Steady-state frequency curves misrepresent how transient music interacts with reflections. — Directly analogous to the reader’s existing emphasis on how measurement methodology shapes what we conclude about acoustic perception — parallels the noise research in One Square Inch of Silence about how measurement choices frame the problem.
• Real-room reflections are attenuated and delayed, not equal-level and immediate. — Connects to the author’s broader theme across the book that textbook depictions oversimplify real acoustic behavior in rooms — also links to audio engineering critiques of oversimplified ‘comb filtering’ claims.
• Acoustical materials alter reflection spectra, invalidating broadband measurements for audibility — Connects to signal processing knowledge about matched filters and why narrowband vs broadband correlation matters.
• Natural room reflections never exceed direct sound, so precedence always holds — Directly relevant to audio mixing and reproduction—links to why multichannel panning can break the precedence effect that natural acoustics never would.
• Delayed lateral sound can exceed direct sound by 10 dB before perceived equally loud — The Hass effect equal-loudness limit is a classic psychoacoustic datum relevant to sound reinforcement and mixing practice.
• Humans are least sensitive to delayed sounds emerging from the same speaker — Echoes the later discussion of comb filtering in the loudspeaker itself and relates to audibility thresholds typical of the psychoacoustics-of-reflections literature.
• Reverberation extends the fusion zone in which reflections merge with the direct sound — Links to the earlier audibility-threshold discussion and to how recording/program reverberation masks or extends perception of room reflections.
• Phantom stereo images resist lateral-reflection interference as well as real images do — Connects to summing localization and stereo phantom imaging, relevant to any loudspeaker-room system design work.
• Precedence effect threshold curves hold stable across very different listening environments — Connects to Haas precedence-effect literature and the room-acoustics vs anechoic debate central to psychoacoustic measurement methodology.
• Detecting reflected sound depends heavily on the continuity of the source signal — Connects to the broader psychoacoustic finding that continuous signals mask reflections far more than transient ones; links to precedence effect literature.
• Fibrous absorbers become ineffective below roughly a quarter-wavelength thickness. — Connects to the reader’s deep interest in measurement methodology: the visual seduction of impulse responses showing only high-frequency removal.
• Multichannel and immersive audio reduce the perceptual importance of small-room reflections. — Connects to the reader’s prior interest in whether small-room acoustics matter when recordings carry their own spatial cues; ties to Section 5.8 on recordings of large spaces masking loudspeaker flaws.
• Natural room reflections are too weak and early to please listeners of reproduced speech. — Reinforces the earlier precedence-effect material; the fusion zone concept links to how comb filtering and echo perception are managed in loudspeaker design.
• Listeners tolerate second images in music because spaciousness outweighs them. — The precedence-effect boundary here is the perceptual pivot; connects to the earlier definition of fusion zones and to how concert-hall acoustics condition listener preferences.
• Acoustical interference dips are too unstable to be evolutionary localization cues — Relates to the claim that peaks matter more than dips in perceived sound quality from earlier chapters on loudspeaker response.
• Elevation localization is a timbral recognition task driven by resonant peaks — Extends the peak-vs-dip sensitivity finding from sound quality research into localization; ties chapters on loudspeaker response to spatial hearing.
• Horizontal localization uses binaural cues while vertical localization does not — Connects to ITD/IAD binaural cue theory from psychoacoustics fundamentals; the contrast with elevation cues is foundational for understanding HRTF.
• Listener expectations, not acoustic cues alone, drive perceived spatial location. — Echoes ventriloquism effect and top-down perception concepts familiar from auditory scene analysis literature (Bregman).
• Atmos up-firing speakers exploit ceiling bounce because elevation cues are high-frequency. — Connects to practical loudspeaker design tradeoffs (off-axis response above 6 kHz) relevant to speaker evaluation.
• Larger recorded spaces perceptually dominate smaller playback spaces — Links to fundamental psychoacoustics principle that larger recorded spaces perceptually override the playback room, relevant to immersive audio design.
• Listeners prefer reverberation times of 1-1.1 s for piano in living-room-sized spaces — Connects to Sabine’s foundational work on reverberation, standard material in Helmut Haas, Wallace Sabine literature.
• Reflections arriving from about 50-70 degrees lateral maximize perceived spaciousness. — Connects to the reader’s general knowledge of binaural decorrelation metrics (IACC) as the standard correlate of perceived spaciousness.
• Spaciousness comes from natural room reflections, recorded multichannel reflections, or both. — Ties directly to why spatial impression from lateral reflections can be captured in multichannel recordings rather than only coming from room acoustics.
• Perceived loudspeaker sound quality depends only on amplitude responses — Connects to the sound power and directivity measurement story of modern loudspeaker review practice.
• Spaciousness dominates pleasantness more than sound quality does. — Relates to the reader’s focus on spatial psychoacoustic models and their application to loudspeaker/room design.
• Adding rear speakers at matching angles does not improve spatial illusion — Connects to the broader theme of perceptual essence vs raw channel counts; also relevant to the reader’s understanding of why quadraphonic sound failed historically.
• Loudspeaker angular separation, not rear placement, drives spatial immersion — Builds on the perceptual essence idea from Section 3.4; the angle diversity rather than channel count is the mechanism driving IACC improvement.
• Side-positioned surround loudspeakers are preferred over rear placement, known since 1971 — Connects to later chapters on multichannel speaker placement and dipoles/direct radiators in home theater setups; also relevant to the reader’s work on psychoacoustic models of ASW/envelopment.
• Frequency-dependent interaural cross-correlation measures sound-field reconstruction fidelity. — Connects to envelopment research and how perceptual models of spatial reproduction are validated both subjectively and objectively.
• Multiple listeners off the sweet spot need extra channels for envelopment. — Connects to sweet-spot discussions in multichannel audio and the trade-off between single-listener fidelity and audience coverage.
• Quadraphonic forced vinyl playback bandwidth to 50 kHz, improving LP quality — Relates to the general principle that format wars and dead-end formats often leave lasting technology legacies, as with other abandoned audio/video standards.
• Cinema, not music, has driven every expansion of audio channel count — Complements arguments about how content domains (not just listeners) shape format adoption across media history.
• Decorrelation of surround channels solved in-head localization in home theaters. — Connects to the reader’s psychoacoustics work on binaural cues and interaural decorrelation as a perceptual cue for spaciousness.
• Bass management lets small loudspeakers deliver full-range sound — Connects to the bass-in-small-rooms theme that Chapter 14 (Welti) develops; also resonates with the reader’s interest in psychoacoustic models of bass perception and subwoofer placement.
• A multichannel system need not compromise stereo quality — Reverses the common audiophile assumption about floor-standers; relates to the reader’s knowledge that preference ratings are dominated by spectral flatness, not box size or format.
• Dipole surrounds only worked for one row of listening positions — Connects to the broader theme in this book and the reader’s ‘One Square Inch’ work about sound fields in small rooms - diffusion requires large acoustic spaces.
• Sound-power specifications only make sense in diffuse fields impossible in small rooms — Directly relevant to the reader’s psychoacoustics goal - sound power as a spec assumes diffuse-field conditions, connecting to room acoustics theory elsewhere in the book.
• Constant beamwidth transducers deliver uniform sound levels over large areas — Connects to line arrays and horn directivity designs familiar in pro-audio and cinema work.
• Early side-wall reflections range neutral to beneficial with well-designed loudspeakers — Connects to general room acoustics treatments for home studios and the absorption-vs-diffusion decision common in audio engineering practice.
• THX dipole surround speakers degraded direct sound while failing to create genuine diffusion. — Connects to the reader’s interest in psychoacoustic models of spatial perception - the claim that reflected sound must arrive from directions that produce interaural differences connects to binaural hearing research.
• Film mixes with expanded dynamic range strain dialog intelligibility — Relates to the reader’s existing work in one square inch of silence on noise annoyance and hearing protection; ties volume, intelligibility tradeoff adjacent to hearing conservation themes.
• Low frequencies travel through structure walls and floors more than highs — Connects to the ‘trees as infrastructure’ article’s theme of physical propagation, though tangential; better matches Toole’s room-acoustics material generally.
• The listening room’s influence on sound diminishes as channel count increases. — Connects to the transition/Schroeder frequency concept from Chapter 5 of this book, and to the general psychoacoustic idea that multiple strong direct sounds reduce reliance on room reflections.
• Most recordings are abstract constructions, not accurate reproductions of live music. — Echoes the larger theme in this book about objective accuracy vs. subjective preference; connects to early chapters on loudspeaker evaluation.
• A mono center channel suffices because vision dominates perceived sound location. — Connects to the ventriloquism effect in multimodal perception literature and to ‘A Midwife’s Tale’-adjacent studies of sensory dominance — actually connects to classic auditory scene analysis work by Bregman and the McGurk effect.
• Object-based audio sacrifices sound quality but suits transient effects; fixed images suit music. — Connects to the Chapter 5 finding (already in the reader’s notes) that listeners accept quality flaws in complex sound fields.
• Multiple independently-processed subwoofers tame room resonances for wider listening areas. — Connects to earlier chapters’ treatment of room modes and bass management — multiple subwoofers spatially average modal peaks.
• Dolby’s 100 Hz Atmos crossover risks localizing subwoofers but is accepted for simplicity — Connects to earlier chapters on bass management, subwoofer placement, and room-mode equalization tradeoffs.
• Room curves show loudspeaker results, not targets worth equalizing toward — Connects directly to the critique of equalizing flawed loudspeakers to match reference curves, echoing debates in loudspeaker correction software (e.g. Dirac, Audyssey) about whether flat in-room response equals good sound.
• High-frequency loss with distance provides a perceptual cue for judging sound source distance — Connects to the earlier chapter material on space perception and distance cues; also ties to Section 12.3.7 the author cross-references.
• Hearing spans a pressure range greater than a million to one — Connects to the physical stimulus side of psychoacoustic modeling, foundational to everything in the reader’s psychoacoustics studies.
• Doubling perceived loudness requires a 10 dB increase. — Core psychoacoustic scaling rule linking stimulus intensity to perceptual loudness—central to the reader’s modeling interest.
• 16-bit CD audio suffices for most program material while 24-bit exceeds delivery needs — Connects to the ongoing loudness vs dynamics debate in audio engineering; contrasts with the loudness war practices discussed elsewhere.
• Recording studio background noise should approach the hearing threshold — Connects to the One Square Inch of Silence material on ambient noise floors and what characterizes a quiet room.
• Minimum-phase reasoning lets frequency responses alone reveal room resonance behavior. — The inferential leap from amplitude to time domain is a methodological principle applicable across measurement-driven engineering fields.
• Steady-state frequency response is the reliable indicator of audible room resonances — Connects to the broader theme that measurement display methods shape conclusions in other fields (see James Gleick / visualization bias discussions).
• Multiple independently-processed subwoofers tame room resonances for wider listening areas. — Relevant to the ADDENDUM article on trees-as-infrastructure’s broader claim about spatial arrangement shaping resonant behavior — actually more relevant to Toole’s own later chapters on multi-sub bass management.
• Spectral variations inside one critical band alter perceived timbre — Connects to Moore’s ERBN work and the psychoacoustic accounting of roughness/beats — relevant to the reader’s model-building interest in how reproduction systems shift timbre.
• Listeners prefer flat amplitude response but are insensitive to phase shift — Connects to the reader’s psychoacoustic modeling focus: waveform fidelity and phase audibility are central to models of perceived sound quality.
• Half-wave rectification in the inner ear does not make polarity reversal audible — Ties to the reader’s interest in how physical stimuli (eardrum movement) cause perceptual responses; the half-wave rectifier argument is a mechanistic hypothesis that failed empirically.
• Hearing loss widens critical bands and alters music perception itself — Widened critical bands in hearing loss ties to the reader’s psychoacoustics modeling interest and to masking/frequency-resolution material elsewhere in this book.
• Phase shift is largely inaudible for reproduced music in reflective rooms — Connects to the earlier chapter discussion of the 7.0-7.4 Fidelity Rating speaker whose linear phase did not save it; phase linearity is empirically subordinate to off-axis response.
• Low-frequency phase shift accumulates massively across every stage of the signal chain — Pays off the earlier 7.0-7.4 rating discussion: even perfect transducer phase is swamped by upstream accumulated phase the speaker cannot correct.
• Music’s dense spectrum masks its own distortion products. — Directly relevant to the reader’s stated goal of linking psychoacoustic models to audio engineering applications.
• Occupational hearing guidelines allow damage, not prevention of loss. — Connects to the reader’s established interest in noise and hearing damage from titles like ‘One Square Inch of Silence’ and ‘The Soundscape.’
• Percentage distortion metrics include inaudible masked components and mispredict perceived quality — Directly parallels the critiques of objective audio metrics elsewhere in this book and in perceptual audio coding literature — measured numbers vs. perceived quality.
• Upward masking makes intermodulation difference tones more audible than harmonics — The upward masking asymmetry (Figure 9.14) is a core psychoacoustics principle; connects to how spectral masking shapes perceptual salience, relevant to any masking-based audio model.
• Conventional distortion metrics cannot predict human response to music or movies — Connects to the reader’s broader interest in why technical audio measurements (THD, IMD) so often fail to predict listener preferences — a recurring theme in loudspeaker reviews and subjective vs. objective debates.
• Consumer loudspeaker distortion is masked at normal listening levels. — Directly builds on the reader’s psychoacoustic interest in auditory masking — distortion escaping notice because it is masked by the signal itself, echoing earlier material on masking thresholds.
• Playback in noisy environments is shrinking audio dynamic range. — Relates to loudness-war discussions and the reader’s psychoacoustic interest in masking by background noise — dynamic compression as a response to masking in real listening environments.
• Measuring power compression properly needs broadband program-like conditioning signals — Connects to audiophile reviewer methodology debates and the challenge of replicating real-world listening conditions in lab measurements.
• As wavelength shrinks below diaphragm size, speakers beam and off-axis sound diverges spectrally — Connects to the cone-and-dome loudspeaker design tradeoffs and to psychoacoustic work on how off-axis vs direct sound energy affects perceived timbre and spatial impression.
• Modern crossovers no longer produce audible artifacts, defeating single-driver speaker advocates — Relates to graph — as a ‘linear’ claim that contradicts typical audiophile preference for full-range single-driver designs.
• Diffusing surfaces serve performance spaces, not home reproduction rooms. — Distinguishes the acoustics of live performance venues from the physics of sound reproduction — a core boundary the reader’s larger project on rooms and loudspeakers depends on.
• Diffusers manipulate only part of the spectrum and can act as absorbers when fabric-covered — Connects to the caveat-emptor theme about specsmanship that runs through audio and hi-fi literature generally.
• Simple loudness-compensation bass boosts cannot work for dynamic-range music — Connects to the Milgrom idea that simple rules fail in the face of system complexity; also to psychoacoustic equal-loudness literature in general.
• Accurate reproduction requires flat response at near-original playback levels — This is the classic loudness-matching problem relevant to home-listening vs reference-monitoring debates.
• Loudness compensation reduces effectively to a bass tone control — Connects to the loudness-vs-level discussion in earlier chapters and to Fletcher-Munson curve applications in consumer audio.
• Room curve variations across control rooms distort recordings’ spectral balance — The ‘circle of confusion’ resonates with the reader’s interest in how listening conditions shape what gets encoded — parallels the social construction of audio standards.
• Home theater owners routinely reduce volume by 10 dB or more — Connects to the reading purpose of psychoacoustic loudness models — a 10 dB cut is half perceived loudness, illustrating the nonlinear loudness scale central to psychoacoustics.
• Consumers prefer boosted bass, a forgivable audible sin — Links to Fletcher-Munson equal-loudness contours: the preference for bass boost reflects the ear’s low-level sensitivity drop at low frequencies, tying to the reader’s psychoacoustics focus.
• Listeners judge loudspeakers equally well on studio-produced popular music — Connects to how studio-monitoring tradeoffs and close-miking shape sound quality perception; parallels ear-training debates in audio.
• Knowing product identity biases listening judgments through the placebo effect — Channels the wine-tasting and drug-testing blind-methodology parallels into audio; builds on the prior paragraph’s subconscious-baggage observation.
• Musicians make poor or unreliable subjective loudspeaker evaluators — Connects to the chapter’s overarching theme (Section 1.4) that experimental method, not listener identity, determines what can be heard — and to the general finding that trained listeners’ opinions diverge from ordinary ones.
• Sighted evaluations stress trained listeners who no longer accept visual bias. — Connects to studies showing visual cues bias subjective product evaluation across domains.
• Most reproduced program content is effectively monophonic — Connects to the argument in this book’s other chapters about why mono testing remains valid — and to the general principle that the two ears receive highly correlated signals in most real content.
• Listener fatigue objections can be answered by self-paced switch testing — Connects to the broader methodology question of how controlled listening tests trade ecological validity (musical pleasure) for discriminative power — parallels double-blind test design tradeoffs discussed in psychology of experiment design.
• Listeners perceptually normalize familiar rooms to judge loudspeakers clearly — Directly relevant to building psychoacoustic models of room-effect normalization; contrasts with the Schroeder-frequency resonance physics also at play.
• Random loudspeaker repositioning across listening seats eliminates room-position bias — Connects to the classic experimental-design insight that randomization controls nuisance variables — parallels randomized block designs in statistics.
• Buffered listening environments mask off-axis loudspeaker flaws and bias evaluations — Recalls the recurring theme that off-axis response predicts perceived quality; connects to earlier chapters’ directivity work.
• Head-tracking with measured impulse responses strongly improves sound externalization — Directly relevant to psychoacoustic modeling of spatial hearing and HRTF-based rendering — core to the reader’s stated goal.
• Preferred TV and film dialog playback levels vary widely across listeners. — Listener preference spread (~20 dB range across individuals) connects to broader claims about individual differences in hearing and the impossibility of a single ‘correct’ level setting.
• Louder sounds are perceived as having more bass and bias subjective comparisons. — Connects to equal-loudness contours and how level changes perceived spectral balance — relevant to audio engineering claims about loudness war in music mastering.
• Standard studio calibration levels are measurably too loud for typical listeners — The warning that unpublished listening levels make test results hard to interpret echoes methodological skepticism familiar from other psychoacoustic testing literature.
• Speaker wire and cables show negligible audible differences under controlled tests — Connects to the audiophile-vs-measurement debate and to human perceptual limits; echoes the reader’s deep interest in psychoacoustic models versus subjective bias.
• Program material and recording quality strongly determine audibility of speaker defects — Connects directly to the reader’s psychoacoustics thread: ‘recording chain accuracy limits what audio evaluations can reveal’ is a classic audio-engineering caveat.
• Recordings with broadband spectral variations still reliably reveal loudspeaker resonances — The circle of confusion (first mentioned in Chapter 1) recurs here as the basis for the claim that spectral program variations don’t mask technical flaws.
• Sub-2-ohm speaker designs caused the amplifier differences reviewers praised — Connects to the book’s broader argument that measurement-blind subjective reviewing confuses the cause of audible differences.
• Hi-fi enthusiasm predicts listening reliability better than musical training does — Connects to How We Listen debates and the trained-vs-untrained listener literature in psychoacoustics; also echoes Ch. 1 contrast between objective measurement and subjective preference.
• A blind-versus-sighted test was designed to expose the influence of visual bias — Connects to the wider literature on expectation and bias in sensory evaluation, e.g. wine-tasting and other blind-versus-sighted experiments.
• Visual appearance of loudspeakers shifts listener preference ratings — Connects to the general literature on sensory bias and blind testing (e.g., wine tasting studies where labels shift ratings), and to sighted-vs-blind evaluation methodology debates.
• Sighted listeners recall prior ratings and ignore audible position differences — Connects to memory-bias and anchoring effects in evaluation; also to the Law of Small Effects debate in sensory evaluation.
• Listener expertise and gender shape rating patterns in loudspeaker evaluations. — Connects to standard listening-test methodology debates about who participates in subjective evaluations — relevant to reading about hearing thresholds and listener panels in psychoacoustics.
• Hearing loss impairs spatial sound separation, not just frequency detection. — Connects to head-related transfer function and auditory spatial localization literature; also to the reader’s existing knowledge of room acoustics.
• Hearing-impaired listeners give inconsistent sound-quality ratings unlike normal-hearing subjects — Connects to the ‘circle of confusion’ concept in Chapter 1 and to the general theme of how expert listening judgments depend on intact hearing.
• Listener judgment reliability declines with age and accumulated noise exposure — Connects to the reader’s broader theme of small acts of decorum toward corpses — here aging experts’ reliability fades; also connects to psychoacoustic training literatures.
• Naive and trained listeners agree closely on loudspeaker quality ratings — Directly relevant to the reader’s stated goal of psychoacoustic models — listener-selection methodology underpins all subjective loudspeaker ratings.
• Consumer Reports killed its loudspeaker reviews after research disproved their methods — Ties to chapter 11’s Harman research; a cautionary story about seemingly scientific measurement practices.
• Psychoacoustic loudness models cannot accurately predict individual listener responses — Relates to the reader’s broader interest in psychoacoustic modeling limits; Moore’s own caveat connects to the general problem that model accuracy falls at the individual level, echoing themes in other psychoacoustics texts.
• Subjective judgment remains the ultimate reference for loudness measurement schemes — Connects to research methodology in psychoacoustics and how measurement schemes always trace back to subjective anchors.
• Sound power alone does not predict loudspeaker sound quality. — Connects to the broader spinorama measurement methodology Floyd Toole developed, and foreshadows why single-number power-based accuracy scores fail.
• Sound power alone cannot predict listener preference for loudspeakers — Refutes the premises of flat/neutral speaker evaluation rooted in power-based measurements; links to Harman target curve research and Olive’s SPINorama work.
• Listener preference is driven mostly by timbral neutrality across the listening window — Connects to Olive/Harman spinorama and NBD/SM smoothness metrics used in loudspeaker measurement literature.
• Perceived spectral balance matches on-axis response more than sound power or room curve — Connects to the direct-vs-reverberant precedence debate and to Olive’s finding that on-axis flatness is a perceptual requirement.
• Loudspeaker resonances are the primary cause of poor sound quality. — Ties to room-acoustics control needs in both professional and consumer contexts.
• Fine-grained anechoic measurement statistics can near-perfectly predict listener preference rankings — Directly relevant to how spinorama presentation and room curve prediction are built and applied.
• Statistically confirmed listener preference for neutral timbre with deep bass — Connects to the general theme in reviewer skepticism literature that unvalidated subjective review claims can be contradicted by measurement-grounded research.
• Trained listeners can verbally connect sound preference to measurable on-axis and listening-window curves — Connects to the broader research stream on how trained listeners can verbalize perceptual dimensions in physically measurable terms, a marker of mature psychoacoustic modeling.
• A well-furnished domestic room can already provide acceptable reverberation times for listening. — Connects to how the NRCC listening room figures throughout earlier chapters as the canonical domestic-model for loudspeaker evaluation.
• Home theater RT targets demand costly low-frequency absorbers yet ignore the resonance problem. — Foreshadows Chapter 14 on resonance solutions — the real treatment for low-frequency problems.
• Constant-beamwidth-transducer speaker arrays hold stable loudness across listening distance — Connects to the earlier CBT/Legendre shading material at 1293 and to general psychoacoustic loudness-distance invariance literature.
• Critical distance is ill-defined in small rooms because short reverberation times fail steady state — Connects to the general idea that models validated in large halls break down in small rooms, echoing Toole’s core thesis about domestic listening spaces.
• Loudspeaker off-axis response dominates in-room energy at the listening position. — Reinforces the spinorama/measurement discussion in Chapter 2 — off-axis response as the key in-room determinant.
• Seat-caused acoustical interference eludes equalization and often goes unnoticed by listeners — Comb-filtering and non-minimum-phase interference connects to room equalization debates seen earlier in the book and to Toole’s broader argument that excessive EQ harms perceived quality.
• Sound power predicts room response for omnidirectional speakers while directivity shapes room curves — Connects to the loudspeaker directivity and room-curve discussions in earlier chapters (Figure 9.15 referenced, listening window concept from prior chapters).
• Standing versus seated position changes perceived sound quality only insignificantly — Stand-up/sit-down insignificance connects to the binaural adaptability point raised in the previous paragraph — listeners filter out positional acoustical artifacts.
• Elevated microphones above 400 Hz congregate, reducing seat-related measurement anomalies — Directly continues and resolves the measurement-anomaly theme from locations 1331-1333: the practical mitigation for seat interference is raising the microphone at least 60 cm above seat backs.
• Harman’s calibration target curve encoded deliberately tilted in-room response, not flat room response — Connects to Olson/Toole’s evolving debate about flat in-room vs. tilted targets, and to the reader’s broader psychoacoustics interest in how perceived sound quality maps to measured response.
• Untrained listeners in method-of-adjustment tests prefer the boosted “happy face” spectrum. — Connects to the contrast between free choice in adjustment tasks (readily revealed preferences) and blind A/B rankings — echoes findings elsewhere in preference psychology about expressed vs. revealed choice.
• Consumer tone control use disrupts program translation across systems. — Connects to the ‘circle of confusion’ concept central to this book and to Toole’s broader argument that flat direct sound is the reference standard.
• Random-incidence absorption coefficients fail to predict actual reflected spectra — Connects to the reader’s interest in psychoacoustic models — the standard published absorption data systematically mischaracterizes what a listener actually hears from an early reflection.
• Fiberglass density barely affects absorption but strongly affects mechanical strength — Connects to Figure 12.23 finding that two different fiberglass densities measured essentially the same acoustic behavior.
• Sound angled into absorbers absorbs more by traveling through more material — Connects to Chapter 2’s Figure 2.10 documenting actual early-reflection incidence angles of 45-60 degrees.
• Fiberglass reflection depends on angle and frequency, not density — Reinforces location 1370’s density-independence claim, this time cross-validated by two independent measurements.
• Bass traps’ inadequacy pushed Toole toward multi-subwoofer mode control. — Connects to the multi-subwoofer mode manipulation methods detailed in Chapter 14 — a cross-chapter causal thread in Toole’s own practice.
• Randomly spaced hemi-cylinder diffusers work far better than contiguously placed ones — The spatial-regularity-kills-performance pattern echoes diffusion panels in RF/EM wave engineering — regular spacing creates specular coherent behavior.
• Commercial loudspeaker engineering requires translation across varied sources and listeners — Connects to the translation concept discussed in earlier chapters on loudspeaker evaluation methodology.
• Even expert engineers are biased by non-auditory factors in loudspeaker evaluation — Connects to the reader’s prior interest in controlled experimental methodology; touches on bias and perceptual evaluation paralleling halo-effect research.
• Early reflections within 30-40 ms improve speech intelligibility — Extends the earlier-chapter theme of early reflections and precedence effect in perception of sound in rooms.
• Multichannel recording content masks room acoustics and loudspeaker resonances — Connects to earlier chapter 5 finding that mono/hard-panned listening separates speaker from room; this paragraph extends the mechanism into multichannel perception.
• Loudspeaker evaluation requires mono, while enjoyment happens in multichannel — Directly relevant to the reader’s goal of linking models to real applications — this is a practical methodological consequence of the psychoacoustic masking mechanism.
• Deep broadband diffusers can create a 30 dB immediate reflection drop — Connects to the craft of room design: the measured ETC profile (30 dB early drop, 0.3 s RT) is a concrete design target a reader modeling room acoustics could replicate.
• Mini-reflections perceptually add up beyond what visual reflection analysis predicts — Connects to the reader’s prior material on how spatial information in more channels makes the room less of a factor — relates to immersive audio formats.
• Air space behind absorbing panels cheaply improves absorption performance — Connects to the standing ADDENDUM piece on trees as infrastructure only loosely; more directly a practical build tip worth pairing with absorber design notes in the reader’s audio setup knowledge.
• Room diffusion is not required for perceived spaciousness — Connects to multichannel spatial audio design where the program signal, not the room, creates envelopment.
• Diffusers mainly attenuate specific reflections rather than create diffuse fields — Reinforces the thesis that program content, not the room, should produce spatial effects in multichannel reproduction.
• Perfect diffusion is an unattainable ideal in real rooms — Connects to the measurement-laboratory variation problem in absorption coefficient testing, parallels the reproducibility issues in lab measurement discussed elsewhere in acoustics literature.
• Near-field sound measurement is unreliable when multiple source parts radiate simultaneously — Interference between radiating elements causing position-dependent irregularities parallels the multi-speaker comb-filtering and interference physics covered elsewhere in this book.
• Spatial averaging of measurements suppresses interference artifacts while preserving spectral information — Connects to the spinorama measurement convention widely used in loudspeaker reviews and industry testing.
• Influential early analysis found truncated line sources have little to recommend them — Connects to the line-source modeling literature from Lipshitz & Vanderkooy (1986), relevant to audio engineering debates about line arrays vs. point sources.
• A single boundary reflecting sound off an omnidirectional source creates frequency-dependent interference lobes — Complements the room-boundary reflections discussion from earlier chapters on comb filtering and early reflections in loudspeaker-room interaction.
• Controlled measurements confirm the theoretical boundary-gain relationships at low frequencies — Connects theory to empirical validation protocol — anechoic chamber plus outdoor parking-lot boundary tests, a model of controlled psychoacoustic measurement.
• Reflections from adjacent walls create destructive interference nulls at one-half wavelength spacing. — Connects to the standing-wave and room-mode material of Chapter 14; the 188 Hz null is the direct manifestation of the standing-wave pattern concept in a simpler, adjacent-boundary case.
• Room standing waves mask the adjacent-boundary effect even after averaging. — This mirrors the ‘grafting and growth’ methodological tidiness — clean field measurements vs. messy in-room reality — and the challenge of isolating single mechanisms inside a complex system.
• Spatial averaging and in-situ power measurement reveal identical boundary effects — Power radiation vs. spatial average convergence also appears in diffuse-field and room absorption measurement theory.
• Boundary distances tuned to be unequal and non-multiples minimize frequency-response variations — Connects to the placement-strategy family of room-acoustics recipes seen across audio literature.
• Smaller drivers radiate more omnidirectionally at a wider frequency range — Connects to typical loudspeaker design tradeoffs - baffle-step and driver-size-directivity relationships familiar from any loudspeaker design text.
• The cancellation dip shifts to higher frequencies and weakens as measurement moves off axis. — Connects to boundary-interference concepts from earlier chapters on comb filtering and dipole-style cancellation dips.
• Sitting close to a rear wall creates early strong reflections that corrupt perceived sound — Extends the reviewer-chair anecdote in 1502 into the underlying causal mechanism of boundary proximity creating early strong reflections.
• Front loudspeakers are designed without regard for their boundary settings — Connects to the chapter’s overall theme on adjacent-boundary effects and the irony that the most important channels get the least boundary consideration.
• Rear-boundary reflections add decorrelated sound that degrades imaging and soundstage — Links to the precedence effect / Haas effect literature on how delayed uncorrelated reflections blur localization.
• Commercial room-calibration algorithms vary so widely that results are not directly comparable. — Connects to the earlier discussion of room equalization in Section 12.3.3 and to the ‘circle of confusion’ consistency objective from Section 1.7.
• Opposing in-phase subwoofers cancel odd-order axial modes but amplify even-order ones. — Core psychoacoustic mechanism: how symmetric drive phasing selectively acts on mode order parity — connects to the reader’s interest in how physical stimuli cause perceptual responses.
• Multiple identical subwoofers reduce seat-to-seat bass variation — Connects to the later optimized-subwoofer-configuration material and to the general theme of modal control in room acoustics.
• Subwoofer placement conclusions were validated across many room dimensions. — Welti’s MATLAB modeling and published VSA data bank are openly available at Harman’s site for replication.
• Knowing any two of room dimensions, subwoofer layout, and seating enables optimizing the third. — This three-parameter optimization framework mirrors the design-method approach of choosing two knowns to solve for the third seen in engineering and acoustics.
• Corner subwoofer placement maximizes bass efficiency but worsens seat-to-seat consistency. — Connects to placement-optimization tradeoffs discussed in earlier chapters on subwoofer/low-frequency reproduction.
• Computer-assisted search is needed to optimize bass in non-rectangular rooms — Connects to modern room-correction software (e.g. Dirac, Audyssey MultEQ) making automated bass optimization mainstream.
• Multiple subwoofers allow cheaper units at positions needing reduced drive — Practical cost-savings implication connects to any loudspeaker/room-system design discussion; a 6 dB gain reduction means wattage needs drop to 25%.
• Additional distributed subwoofers with optimization outperform EQ while using less power. — Concrete real-world demonstration of the multiple-subwoofer distributed approach’s superiority, supports the general principle treated throughout this chapter.
• Subwoofer placement severely impacts the electrical power needed for equal low-bass output. — Connects to the 8.7x power penalty figure and MOL concept, relevant to understanding how room acoustics imposes real energy costs beyond perceptual ones.
• Multiple optimized subwoofers let a single global EQ filter flatten bass for every listener. — Makes the 7 dB / one-fifth-power relationship concrete — a useful quantitative anchor for how much headroom modal control buys.
• High-resolution measurement and matched Q are required for effective modal EQ. — Directly actionable for the reader’s stated goal of understanding psychoacoustic modeling and applications — EQ resolution vs resonance Q is a core model-tuning issue.
• Equalization and listener repositioning can produce nearly identical results for room modes. — Connects to Floyd Toole’s broader theme that both room treatment and EQ address the same underlying resonance; the ‘monster mode’ framing echoes earlier chapters on modal peaks.
• Equalization masks a mode’s audibility but only for reproduced sound. — Echoes the recurring theme that room treatment vs EQ solve different problems — modal suppression through physics vs masking through signal processing.
• Notching a room mode reduces woofer distortion and lets louder playback — Directly relevant to the reader’s psychoacoustics focus: EQ’s side-benefits beyond the frequency response — reduced driver excursion and distortion.
• Source and receiver placement effects on modes occur at all frequencies — Connects to why listener/speaker positioning (the placement debate in room acoustics) shifts response everywhere, not just at resonance peaks.
• Resonant peaks bother more listeners than nulls because they occupy most of the room — Connects to the audibility asymmetry between peaks and dips discussed at chapter 9’s sections 9.6.1/9.6.2 — a recurring tradeoff in low-frequency perception.
• Equalization and mode cancellation both reduce bass resonance ringing despite different mechanisms — Ties to the tone-burst waveforms of Figure 5.4 (build-up/decay of resonant energy) mentioned in the passage, and to Section 9.4 loudness halving per 5 dB cited in the next paragraph.
• All subwoofers are equally fast at 80 Hz and rooms slow them down — Connects to the book’s earlier Figure 5.4 on ring/build-up and to minimum-phase system theory familiar from filter/signal processing.
• Listeners respond to resonance spectral prominence, not decay rate reduction — Challenges the common assumption that modal (decay-time) EQ is clearly better than simple magnitude EQ, connecting to the reader’s applied work on room correction algorithms.
• Bass-region reverberation-time measurements reflect resonance ringing, not reflected sound — Connects to the reader’s psychoacoustics work on RT measurement interpretation and to Toole’s earlier chapters on room acoustics above transition frequency.
• Resonance detection thresholds rise with higher Q and lower frequency — Directly extends the reader’s psychoacoustic modeling of resonance audibility thresholds across frequency.
• Electronic multi-subwoofer mode control excels because it benefits many listeners at once. — Ties to CABS (Section 14.5.7) and SFM (Section 14.5.8) mode-control methods detailed elsewhere in this chapter.
• Audible resonance decay thresholds rise sharply as frequency decreases — Connects to the reader’s psychoacoustics interest in how perception thresholds differ by frequency — complements decay-time masking thresholds discussed in earlier chapters on sound quality metrics.
• Waterfall diagrams alone poorly estimate the audibility of resonances — Contradicts the common industry habit of relying on waterfall/Cumulative Spectral Decay plots to judge room-mode audibility — relevant to the reader’s modeling of modal behavior.
• Acoustical treatment historically meant absorption, favoring dead rooms — Connects to the reader’s historical interest — commercial absorption since the 1930s and the ‘dead acoustics’ fashion.
• Optimal room ratios as originally conceived are irrelevant to sound reproduction — Connects to classic acoustics literature on room mode optimization (Bolt’s ratios) and why textbook recommendations fail in real reproduction settings.
• Bass level errors cause perceived treble excess and vice versa — This ties into the broader perceptual phenomenon that loudness perception is highly frequency-dependent, matching psychoacoustic equal-loudness work by Fletcher-Munson/Robinson-Dadson.
• Absorption dampens modes and enhances any additional room remedies — Relates to the mode coupling factor concept from Equation 14.2 referenced in the following paragraph.
• Head-tracking with measured impulse responses strongly improves sound externalization — Connects to the earlier book chapters on precedence effect and localization cues (Chapter 5, 14 referenced nearby) that the reader has already covered.
• Head-mounted measurement adds leakage absent from flat-plate fixtures — Connects to measurement-fixture literature and headphone-testing standards the reader already follows.
• Seal leakage makes closed-back headphone bass highly listener-dependent. — Connects to headphone-equalization research and the practical difficulty of personalizing headphones to individual ear/head geometry.
• Open-back headphones deliver the most consistent response across listeners. — The built-in leak rationale parallels how controlled acoustic leaks stabilize bass for open-back designs across variation in seal quality.
• Realistic noise reduction measures require soundscape recordings rather than pink noise. — Connects to the reader’s broader interest in ecologically valid stimuli vs. laboratory artifacts, similar to issues in architectural acoustics.
• ANC headphones sound quality varies with noise environment and noise reduction performance. — Ties to the reader’s psychoacoustic modeling interest: ANC performance as a function of signal context parallels models of masking and perceptual quality.
• DF headphone calibration avoids conflicting HRTF localization cues that make FF sound unnatural — Connects to the reader’s broader psychoacoustics knowledge of head-related transfer functions and localization cues.
• Headphones calibrated to semi-reflective room sound best reproduce stereo recordings made for loudspeakers. — Extends the SRF argument from §1769; connects to the reader’s audio coding and reproduction application interest.
• Tactile seat vibration substitutes for about 3 dB of headphone bass. — The shaker-in-seat bass equivalency connects to the tactile-vibration discussions in earlier chapters and to whole-body vibration in hand-arm/pavement context.
• Listeners are forgiving of headphone resonances but sensitive to bass-level air leaks. — Bass accounting for ~30% of listener preference echoes the loudspeaker preference weighting in earlier chapters; connects to headphone bass-leak variability undermining that dominant factor.
• Listeners strongly prefer the Harman target over DF, Lorho, and FF headphone targets — Relates to Diffuse Field (DF) and Free Field (FF) headphone targets from Møller’s work, foundational psychoacoustic reference curves.
• Listeners over 55 prefer brighter headphones, possibly from age-related hearing loss — Connects to presbycusis literature and to how optimal target curves may need to vary by listener demographics, echoing ideas about individualized HRTFs.
• Headphone sound preferences are remarkably consistent across countries and ages — Cross-cultural consistency of audio preferences parallels findings on cross-cultural consistency in music perception and other perceptual judgments.
• Preferred headphone tone adjustments depend on music program and listener attributes — Circle of confusion concept links back to Section 1.7 of this book, connecting headphone preference variability to recording production chains.
• Listener segmentation analysis can predict headphone preference from demographics — Agglomerative hierarchical clustering as a preference-segmentation method parallels market-segmentation approaches in consumer research and ties to the demographic-preference findings at locations 1793-1795.
• Headphone preference tests used double-blind methods across a wide price range — The virtual headphone double-blind method was introduced earlier in this chapter (presumably at locations covering Olive et al., 2013a methodology) and is the methodological backbone of all these preference studies.
• Audience bass preferences deviate from the Harman target by up to six dB. — Connects directly to the reader’s stated interest in how perceptual preferences (Harman target) are modeled from acoustic measurements.
• Headphone preference ratings can be predicted from objective measurements like loudspeakers’ can. — Ties to the reader’s interest in psychoacoustic models — this is the modeling methodology that converts measured responses into predicted preference scores.
• Below-1 kHz resonances go unpunished by the prediction model despite lowering actual preference scores — The resonance-Q blind spot parallels the loudspeaker finding that narrow resonances matter less than broadband spectral balance — the Q-weighting question recurs across this book’s model development.
• No single ear-simulator correction applies because error is headphone-specific — A methodological caution that parallels transducer-measurement calibration issues in other audio measurement contexts.
• Predicting preference is easier for in-ear than over-ear headphones — Connects to the reader’s broader interest in psychoacoustic prediction models and their accuracy bounds across transducer types.
• The rigorously validated Harman target became the industry’s blind-listening benchmark — Connects to how measured, validated preference curves (like the earlier in-room loudspeaker targets in this book) become industry benchmarks — same validation-through-blind-listening epistemology.
• A commercial reference target derives from flat near-field monitors — Contrasts with the Harman research approach, which was derived from blind listening tests rather than a flat-monitor assumption.
• Ear coupling and head size make headphone sound-quality opinions vary widely — Connects to the reader’s interest in how physical stimuli (fit, coupling, leaks) cause perceptual response (timbre, quality opinions) in psychoacoustics.
• Subjective agreement requires identical delivered signals and matched objective measurements — Core methodological principle for psychoacoustic model building: signal standardization precedes subjective-preference prediction.
• Distinctly different headphone frequency responses can all be equally preferred — Connects to the earlier finding in this book (15.6.4/15.6.5) that women prefer less bass — and complicates the notion of a single universally optimal headphone target, echoing the broader theme that listener preference tolerances are broader than engineering precision suggests.
• Headphone preference tolerances are tightest in the speech-critical midrange. — Echoes earlier chapters’ findings on room-response/target tolerances and the primacy of the midrange for speech and music perception.
• A headphone target curve descends gradually with frequency and boosts bass. — Connects to the Harman target curve concept and the PIR (predicted in-room) response matching a well-designed loudspeaker, a theme running through earlier chapters.
• Headphone preference tests can be run virtually via equalization. — The virtual-headphone methodology is a direct experimental analog of the equalization-based loudspeaker listening methods discussed in earlier chapters.
• The flat DF target fails listening tests mainly due to insufficient bass — Connects to the book’s earlier chapters on the PIR and loudspeaker target responses; the Revel F208 reference frames headphone against speaker voicing.
• Flat frequency targets suit binaural audio while Harman suits stereo — Refines the Harman-target preference findings from earlier chapters; the target is content-dependent, not universal.
• Headphone bass boosts may compensate for missing haptic sensation from loudspeakers — Directly ties back to earlier sections on the loudspeaker-in-a-room bass experience (the bass boost target for loudspeaker reproduction).
• Headphones are the most common device for experiencing spatial audio content — Connects to the streaming-era content accessibility theme; spatial audio’s adoption hinges on streaming delivery rather than hardware.
• Head and ear variation makes fixture measurements unreliable predictors of listening — Connects to the phantom midrange and vertical-polarization debates in headphone research literature.
• Headphone listening increases agreement with and empathy for narrators — Connects to the reader’s interest in psychoacoustic models — in-head localization as a perceptual mechanism driving a measurable behavioral outcome (agreement/compliance).
• Headphones became the primary device through which entertainment is consumed — Connects to the reader’s interest in psychoacoustic models — the shift to headphones as primary playback changes which spatial acoustic models matter.
• Many daily headphone users disbelieve headphones cause hearing damage despite symptoms — Parallels the broader theme of people dismissing chronic sensory harms, echoing the noise-as-blind-danger material from One Square Inch of Silence.
• Mild hearing loss makes trained listeners give inconsistent sound quality judgments — References Section 10.1.2 elsewhere in the book on double-blind listener criteria.
• Chronic noise exposure causes tinnitus and hyperacusis even with hearing protection — Connects to the book’s broader theme of hearing damage and the reader’s own interest in psychoacoustic models of loudness perception.
• Occupational noise standards accept measurable hearing loss and do not protect critical listening — Connects to the reader’s prior work on silence and noise exposure — the One Square Inch of Silence material on noise as danger signal shows how sub-clinical damage accumulates the same way.
• Hearing loss widens critical bands and alters music perception itself — Connects to the critical-band / auditory-filter discussion in earlier psychoacoustics chapters, showing the perceptual consequence of widened filters.
• Hearing loss impairs spatial sound separation, not just frequency detection. — Directly relevant to earlier chapters on stereo/immersive reproduction and localization; hearing-impaired listeners gain almost nothing from 30° of angular separation.
• Audiometrically normal listeners may still have substantial hidden hearing loss — Connects to earlier chapters on spatial hearing and binaural cues; also relates to the immersive-audio applications noted in the next paragraph.
• Movie sound mixers understand dialogue partly because they have rehearsed it — Explains why professional evaluations of loudspeaker/intelligibility differ from consumer experience — relevant to earlier chapters on listener training and preference testing.
• Hearing-impaired listeners equate speech intelligibility with overall sound quality. — Connects to the reader’s existing knowledge of audiometric testing and speech-in-noise perception research; the normal-hearing group’s preference for full multichannel preserves perceptual fidelity while hearing-impaired listeners trade spatial richness for intelligibility.
• Hearing impairment commonly begins between ages 30 and 44 — The onset at 30-44 fits presbycusis literature showing measurable high-frequency threshold shifts beginning in the third decade; couples with the reader’s audiometry knowledge.
• For hearing-impaired viewers, unclear dialogue makes a movie unenjoyable — Pairs with the earlier paragraph’s finding on sound-quality ratings; enjoyment data independently replicate the impaired group’s dialogue-priority result.
• A real center speaker improves dialogue clarity over a phantom center — Connects directly to the book’s own Section 4.3.2 on phantom center imaging and to the reader’s psychoacoustic modeling interests in spatial hearing.
• Loud movie mixes get turned down, dragging dialogue below intelligibility — Illustrates a feedback loop in the signal chain: playback attenuation as a causal mechanism reducing intelligibility, relevant to the reader’s interest in real-world psychoacoustic application.
• Highly regarded loudspeakers measured surprisingly ragged anechoic responses in the 1960s — Connects to modern spinorama-based speaker measurement practice; the discipline has moved from anechoic on-axis curves to multi-angle averaged data.
• The direct, on-axis sound dominates perceived loudspeaker quality in rooms. — Connects to the room-curve vs. direct-sound controversy in loudspeaker reviews and EQ discussions.
• Matching room curves via EQ does not equalize audible sound quality. — Counter-intuitive result relevant to room correction systems like Audyssey/Dirac claims.
• Single-axis measurements misrepresent multidirectional loudspeakers like Bose — Echoes the book’s earlier argument that broadband/spatially-averaged measurements are needed for omnidirectional designs; connects to reader’s notes on measurement methodology in psychoacoustics.
• Modern loudspeakers have converged so far that choice among them is statistically a tie. — Connects to the reader’s prior notes on double-blind listening tests and the limits of anechoic measurement as a differentiator.
• On-axis flatness alone fails without controlled off-axis directivity. — Directly instantiates the causal chain: driver size/geometry → off-axis response → reflected sound coloration in rooms.
• Sighted listening evaluations are biased regardless of listener expertise — Connects to earlier chapters on controlled listening tests (Section 10.1) and the well-documented bias effect in perceptual evaluation.
• Most loudspeakers need equalization to correct low-frequency room resonances — Relates to room-mode and bass-management material in earlier chapters on rooms.
• Technical audio decisions need measurement science separate from artistic opinion — Echoes the subjective-versus-objective divide argued throughout engineering culture; connects to audiophile review controversies and to the ‘honest messengers’ metaphor in paragraph 1955. Seed
• Recorded art translation depends on a shared consumer-professional audio standard — Could frame an essay on how any creative medium’s fidelity depends on a shared receiver-side standard, not just source quality.
• Most listeners can recognize audio excellence when comparing loudspeakers side by side. — An essay angle on why product reviewers’ hearing tests fail: the dominant take-it-home method is the least informative, and how controlled A/B comparison changes results.
• Tube amplifiers audibly color loudspeakers as those become more neutral — Angle for an article: the nostalgia-object status of tube amps and vinyl, where physical ritual outranks measurable fidelity.
• Sighted loudspeaker evaluations are contaminated by non-auditory visual and social cues — Sighted listening bias is a ready-made article angle: why the entire high-end audio review industry is epistemically weakened by non-blind evaluation.
• Listener judgment reliability declines with age and accumulated noise exposure — First-person account of age-related hearing decline is a humanizing, relatable frame for a technical chapter — usable as an intro anecdote.
• The knuckle test misjudges cabinets because contact excitation differs from internal pressure. — A strong anecdote for an essay on how consumer ‘tests’ (tapping, heft) measure the wrong physical quantity, and how manufacturers cynically engineer to pass them.
• Highly regarded hifi loudspeakers had wildly non-flat anechoic responses — The puzzle of why loudspeakers could historically get away with non-flat responses while electronics could not is a good essay angle on measurement vs. perception in audio.
• The variety of loudspeaker sounds in the marketplace originates from uncontrolled subjective evaluations — Angle: how market pressure and informal listening sessions, not engineering targets, shaped the entire loudspeaker industry’s sound character — a history of design-by-vibe.
• Single-stimulus listening relies on capricious long-term memory and yields contradictory opinions — Essay angle: why ‘take it home and listen’ reviews are structurally unreliable — comparison-free evaluation and the capriciousness of acoustic memory.
• Room acoustics were the one loudspeaker variable manufacturers could not control without EQ — Article angle: how government funding politics quietly shaped consumer audio technology via the NRCC-Athena project.
• Objective measurements routinely expose flaws that subjective listening reviews miss — Angle for an essay: the persistent case for blind testing in audio, where accumulated measurement data repeatedly contradict expert subjective judgments.
• Single-number loudspeaker ratings mislead because real faults often have straightforward corrections — An article angle: ‘why loudspeaker ranking numbers are the wrong way to shop’ — the case that anechoic data plus corrective EQ beats a single flawed score.
• Listening window averaging estimates the direct sound heard by a typical audience — An angle for an article on why single-axis anechoic measurements mislead consumers — the listening window concept explains the discrepancy.
• Untrained listeners reach quick, consistent sound-quality judgments when switching is instantaneous and sequence-blind. — An essay angle: the experimental-design lesson that single blind listeners with randomized switching outperform shared-control tests — a general principle for any perceptual/sensory evaluation methodology.
• Most US music is now produced in residential, acoustically poor rooms — Potential angle: how democratization of production tools (Pro Tools) degraded the acoustic quality of the entire music creation chain, and what this implies for the consumer’s realistic expectation of recorded fidelity.
• Recording engineers preferred direct-sound fields partly to mask poor monitor loudspeakers. — An article angle: the history of monitoring practice in recording studios — how technical dogma (near-field monitoring, dead rooms) may have been partly rationalized bad hardware. Engineering culture can adopt practices for reasons no one admits at the time.
• Listeners adapt within minutes to externalize sound even through crude transducer devices — An essay angle on how hearing-protection hardware inadvertently reproduced convincing binaural spatial cues, hinting that minimal cue fidelity plus adaptation suffices for externalization.
• Crosstalk cancellation delivers binaural separation through loudspeakers — Angle for an article or demo note: how virtual surround synthesis from a pair of drivers works and where it breaks down.
• Stereo and multichannel listening make listeners more forgiving of loudspeaker flaws — Article angle: why mono evaluation is the true test of a loudspeaker, and stereo mask its flaws.
• Edison staged deceptive live demonstrations to prove his phonograph was tonally transparent — Could be an essay angle: ‘the original sin of audio’ — how the industry’s very founding pitted technical measurement against carefully curated listening conditions, a tension that still defines audio reviewing.
• Hall reverberation cloaks loudspeaker defects in live-versus-reproduced demonstrations — Angle: how demonstration environments systematically flatter audio gear versus typical home listening—a cautionary piece on judging hi-fi in showrooms versus small rooms.
• Program material choice determines which loudspeaker or room flaws get revealed — A practical essay angle: how choosing test tracks biases what audio reviewers can possibly hear — a critique of speaker-review methodology.
• Responsible listening tests use discriminant-selected programs and within-program comparisons — Could support an essay on how repeated exposure converts musical pleasure into pure test signal — the cost of scientific rigor on listening.
• Automated loudspeaker position switching improves listening-test reliability — A possible angle: why amateur audio reviewers should adopt controlled positional-substitution rigs rather than relying on memory-based A/B/C comparisons.
• Speech and solo instruments reveal loudspeaker flaws least, dense broadband music most — Material for an article on how to actually audition loudspeakers in stores — why the demo track matters as much as the speaker.
• Audible resonance data enables value engineering of cheap loudspeakers — Angle on loudspeaker price vs quality: audibility thresholds let makers spend where it matters, so cheap speakers can sound good — worth a piece.
• Automatic EQ can create unwanted resonances by filling interference dips — Automatic EQ vs. human-informed EQ — an essay angle on why blind signal-processing fixes mishandle acoustical interference that is non-minimum-phase and should not be equalized.
• Standard octave-band smoothing hides the fine structure of comb-filter patterns. — Angle for an essay on how measurement resolution determines which acoustic problems we even see — the epistemology of audio testing equipment.
• Listeners tolerate second images in music because spaciousness outweighs them. — Could build into an article on why ‘accurate reproduction’ may not be what listeners actually want — spaciousness competes with fidelity, and musical content changes the tolerance for artifacts.
• Music benefits from dedicated side channels at ±60 degrees — Angles worth pursuing: a practical guide on why music mixes fail on plain L/R/front setups without front-wide channels.
• The center channel carries most dialog and on-screen sound in movies — Angle: why the most important loudspeaker in a home theater (the center channel) is the one people spend the least on — a practical listener-protection essay.
• Marketing fads can override objective engineering in product design — An essay angle: how certification branding (THX) and market demand can drive inferior technical designs, and how manufacturers quietly subvert them.
• Full-height line sources halve the off-center damage to envelopment — An article angle on how loudspeaker physics constrains the social geometry of listening rooms — who gets the good seat is partly decided by speaker type.
• Opposite-wall reflections compensate for surround propagation loss at no cost — Article angle: the counterintuitive case for keeping reflective walls in home theaters rather than over-treating them with absorbers.
• Listener-level channels, not height channels, drive spaciousness and envelopment — An article angle: ‘why your Atmos system’s sound quality barely matters compared to getting the bed channels right.’
• Immersive systems could cheaply implement room reverb enhancement but none do. — Essay angle: ‘the room enhancement feature immersive audio forgot’ — why a proven, now-cheap enhancement remains absent from modern systems.
• Most commercial Atmos music mixes are embellished stereo rather than true multichannel. — Article angle: the gap between the hype around spatial audio and the actual practice — most ‘immersive’ music is stereo with reverb on top.
• A mono center channel suffices because vision dominates perceived sound location. — An essay angle: why the ‘sound atmosphere’ of cinema is a cheaply engineered illusion — mono center channel does most of the work via the ventriloquism effect.
• Dolby’s 100 Hz Atmos crossover risks localizing subwoofers but is accepted for simplicity — Potential article angle: the tension between engineering best practice (multi-subwoofer room-mode manipulation) and industry-standard one-size-fits-all bass management specifications.
• Graphs in audio reviews can deceive by manipulating axis scaling. — Could seed an essay on how to read audio-review graphs critically—spotting scale manipulation in loudspeaker measurements.
• High frequency resolution in waterfalls forces poor time resolution that misrepresents room decay. — Angle: common audio-forum waterfall plots that look alarming are often artifacts of measurement resolution, not real room problems.
• Listeners prefer flat amplitude response but are insensitive to phase shift — Angle for an article or essay: ‘we like flat amplitude, we don’t like resonances, we seem insensitive to phase shift’ — a compact distillation of what actually matters in loudspeaker design versus engineering fetishism about waveform integrity.
• Loud bass masking spreads upward to cover the voice frequency range — A concrete, teachable insight: mixing engineers and movie sound designers should expect loud bass to mask dialogue.
• Occupational hearing guidelines allow damage, not prevention of loss. — Angle: the 75 dB threshold means ordinary life itself is a slow hearing-loss mechanism, so ‘normal’ hearing is really ‘degraded’ hearing.
• Standing waves create loudness dips at room midpoints — This classic walking-listener demonstration would anchor a piece on how to hear room modes with your own ears.
• Diffusers manipulate only part of the spectrum and can act as absorbers when fabric-covered — Potential article: ‘the acoustical con’ — how visual appeal and tape-measure specs mask devices that degrade sound, relevant to home-theater DIY culture.
• Listeners elaborate on flaws but give short praise to good products — Potential essay angle: why humans are more articulate about what is wrong than what is right — a bias in all product judgment, audio or not.
• Reliable panel listeners show low variance and wide rating ranges — A method-oriented essay on how to build and curate a reliable listening panel for subjective product evaluation.
• Formal listener training plus experience yields the highest rating reliability — Angle: what separates expert vs enthusiast vs professional listeners — a piece on how structured training compounds with field experience, and where mere exposure falls short (retail staff beat untrained visitors but trail trained veterans).
• Visual appearance of loudspeakers shifts listener preference ratings — Could anchor an essay on why blind testing matters across expertise domains, and how even loyal employees’ judgment is overridden by visible cues.
• Hearing-normal listeners give far more consistent loudspeaker quality ratings. — Angle: hearing loss as occupational hazard in audio professions — the people who judge sound for a living are systematically losing the ability to do so consistently.
• Consumer Reports killed its loudspeaker reviews after research disproved their methods — A case study of how measurement-driven ratings that sound rigorous can mislead — an angle for an essay on the gap between technical-sounding methods and valid ones.
• Consumer Reports’ accuracy scores inversely correlated with actual listener preferences. — Article angle: how well-intentioned standardized test scoring can systematically invert consumer guidance — a case study in measurement methodology failure.
• Sound power alone cannot predict listener preference for loudspeakers — Angle: how a flagship consumer-testing organization (Consumer Reports) built an entire rating methodology on an empirically falsified premise, and how a corporate R&D group beat them with randomized controlled listening tests.
• The ITU-R BS.1116 standard is routinely misapplied to loudspeaker evaluation rooms. — Could be an essay angle: how an audio-industry standard written for detecting tiny codec impairments gets cargo-culted into home theater design specs.
• Random-incidence absorption coefficients fail to predict actual reflected spectra — Article angle: the gap between standardized acoustical measurements and what happens when an absorber faces a real room reflection.
• Most commercial diffusers are designed for looks rather than measurable acoustic performance — A skeptical-buyer’s-guide angle: how visual marketing outruns measured acoustic performance in a whole consumer category — parallels Bose/cable/hi-fi snake-oil critiques.
• Too much uncorrelated rear-wall diffusion scrambles center imaging — An essay on why good acoustic measurements can mask bad listening — ‘they measured but they did not listen’ as a critique of objective-only engineering.
• Excessive absorption can degrade speech intelligibility — Angles well as a demystifier: ‘dead rooms hurt intelligibility too’ — counterintuitive acoustics fact for home theater design discussions.
• Desirable room acoustics can be encoded and delivered digitally rather than built — A possible article angle: ‘capturing’ acoustically excellent rooms as signal-processing recipes rather than physical constructions.
• Fabric wall coverings often ruin acoustic design despite being advertised as transparent — Article angle: the war between aesthetics and acoustics in room design, and how decorative choices silently undo engineering.
• Tall speakers with stacked woofers are not true line arrays — Article angle: ‘Why your tower speaker is not a line array’ — debunking a common consumer-audio mislabel with clear acoustical reasoning.
• Curved, Legendre-shaded line arrays exploit floor reflections to maintain constant beamwidth at all frequencies — The CBT concept — using a boundary’s reflection as an acoustic extension of the transducer — is a strong story about exploiting, not fighting, room boundaries in loudspeaker design.
• Computer-assisted search is needed to optimize bass in non-rectangular rooms — Angles toward the algorithmic/computer-optimization side of multi-subwoofer placement — a practical application piece on automated room correction.
• Bass-region reverberation-time measurements reflect resonance ringing, not reflected sound — Angle for an article/essay: why standard RT metrics mislead at low frequencies, and how this gap between measured decay and perceived bass behavior complicates room EQ.
• 3D-printed quintile heads let designers test headphones across a population distribution. — A design-validation approach where products are tested against statistical quintiles of users rather than one average user could be an essay angle on inclusive engineering.
• Headphone bass perception varies with how well headphones seal on each ear — Angle: leakage as the hidden variable in why the same headphone sounds bass-heavy to one reviewer and thin to another — a case for why headphone reviews are unreliable.
• Tactile seat vibration substitutes for about 3 dB of headphone bass. — Angle: real bass in cars and home systems is felt as much as heard — a piece on how reproduced bass is a whole-body event and what that means for headphone versus loudspeaker design.
• Listeners over 55 prefer brighter headphones, possibly from age-related hearing loss — Potential article angle: adaptive headphone target curves that shift with listener age, coupling psychoacoustics with demographic audiometric data.
• Headphone sound preferences vary by gender, age, and listening experience — The finding that older listeners (55+) prefer MORE treble and LESS bass is counterintuitive given age-related high-frequency hearing loss typically reduces perceived treble — this demographic reversal is an essay-worthy anomaly worth investigating.
• Headphone sound preferences vary by gender, age, and listening experience — An angle: ‘the bass gender gap’ — why only 4% of female testers wanted more extended bass, and what that says about how target curves encode a demographic default.
• Below-1 kHz resonances go unpunished by the prediction model despite lowering actual preference scores — The model’s failure on HP6 and HP30 is the interesting gap: a purely magnitude-based (no Q, no frequency) model breaks specifically on above-1 kHz resonances — an angle on where simple preference models hit their limits.
• Headphone retail price shows almost no correlation with sound quality — A consumer-advice essay explaining that the Harman target exists precisely because price fails to predict sound quality — a practical guide for buying headphones by measured response, not price.
• The international standard DF target curve rates worse than alternatives — The proposition that official standards lag scientific evidence is worth an essay on how diffusion-field targets entrenched before in-room preference data arrived.
• Headphone listening increases agreement with and empathy for narrators — Angle: ‘The persuasion physics of in-head audio’ — how the medium of delivery (headphones vs. speakers vs. radio) measurably shifts whether listeners agree with what they hear, with implications for advertising, podcasting, and propaganda.
• Open-ear headphones lack bass and tempt users to raise volume against background noise — Angle: the safety tradeoffs of transparency-oriented headphones vs. sealed isolation — a hearing-health essay framing device choice as a risk profile.
• Modern insert headphones can limit output and measure hearing thresholds — Potential article angle: how consumer headphones are converging with audiometric/hearing-aid hardware and what that means for audiology practice.
• Occupational noise standards accept measurable hearing loss and do not protect critical listening — Angle: the gap between legal hearing ‘protection’ standards designed for factory survival and what audio professionals actually need to preserve is a structural blind spot worth an essay. Define
• Recorded art translation depends on a shared consumer-professional audio standard — Defines Toole’s ‘circle of confusion’ concept of the need for basic agreement between consumer and professional audio reproduction technology.
• Human sound-quality judgments are skewed by expectation biases, not just the sound itself. — Defines expectation bias in listening evaluation as a form of placebo effect.
• Tube amplifiers audibly color loudspeakers as those become more neutral — Clarifies that amplifier ‘transparency’ is a real technical requirement with specific failure modes: impedance drive and clipping.
• Anechoic-data equalization differs sharply from room calibration, which is often misused — Draws a crucial distinction between speaker correction from anechoic data and room equalization/calibration — two confused technologies.
• Some audible complaints are recording format flaws, not playback faults — Establishes the book’s scope: sound quality, direction, and space as three distinct perceptual dimensions; also pinpoints where to attribute audible faults.
• Audio knowledge is best conveyed through discovery history rather than bare facts — Sets the book’s methodological stance: biographical narration as a route to understanding acoustical facts.
• Blind-tested listeners with normal hearing produce reliable, measurement-grade subjective ratings — ‘Normal hearing’ is pinned down operationally: within about 20 dB of audiometric zero over most tested frequencies, covering roughly 75% of the population.
• Room boundary reflections are the second loudest sounds a listener hears — Establishes why anechoic measurements alone are incomplete: the strongest early reflections from room surfaces rank second in loudness to the direct sound.
• Frequency, phase, and impulse responses are mathematically interchangeable descriptions of linear behavior. — Establishes the linear/non-linear distinction central to all loudspeaker measurement discussed later.
• Parametric equalization of minimum-phase resonances also reduces time-domain ringing — Defines ‘minimum-phase’ systems: ones where transient response is predictable from frequency response alone.
• Non-linear distortion generates new frequencies as level-dependent behavior shifts. — Precise definition of non-linear distortion as level-dependent input-output curvature generating extra frequencies.
• Reflected sound fields cannot be corrected by electronic equalization alone — Defines non-minimum-phase phenomena as reflections arriving from many directions at many times, explaining why EQ can’t fix them.
• Microphone choice in recordings biases subjective loudspeaker ratings — Defines the ‘circle of confusion’ concept that recurs throughout the book.
• Double-blind evaluation can identify the most transparent loudspeakers — Defines ‘transparent transducer’ as the goal measurable through double-blind evaluation, contrasting with mere liking.
• The term spinorama derives from rotating the loudspeaker to gather response data — Clarifies the origin and meaning of the now-standard ‘spinorama’ measurement descriptor.
• Published spinorama measurements frequently violate standard resolution requirements and are then unreliable — Clarifies what the ANSI/CTA-2034-A standard requires of spinorama data: adequate frequency resolution, which smoothing and time-windowed FFT both undermine.
• Low-Q resonances become audible at peaks below 0.5 dB in the midrange — Defines low-Q resonances and their audibility threshold (1 dB humps) - relevant to psychoacoustic models of loudspeaker evaluation.
• Audibility gaps in loudspeakers stem from inadequate measurements, not limitations of measurement itself. — Inverts the common audiophile axiom ‘we can’t measure what we can hear’ — the failure is the measurement suite, not the perceiver.
• Room curves are measurement results, not equalization targets, except at bass — Distinguishes on-axis (design target) from room curve (result to observe, not optimize) — a key conceptual distinction in loudspeaker measurement.
• LP tracing distortion arises because cutter and stylus follow different geometric paths — Defines the geometric/physical origin of tracing distortion and stylus mistracking — core psychoacoustic-relevant transducer mechanics.
• Accurate anechoic data plus blind listening tests make psychoacoustic correlations emerge quickly — Defines the methodological prerequisites for valid psychoacoustic correlation research: paired anechoic measurement and controlled double-blind subjective evaluation.
• Anechoic chambers lose accuracy below roughly 80 Hz and require correction. — Clarifies the physical mechanism limiting anechoic chambers: wedge length sets the low-frequency cutoff.
• Horizontal and vertical reflections dominate because they are the strongest first reflections. — Explains the design logic behind full-orbit loudspeaker measurement: the geometry of room reflections dictates which spatial directions matter most.
• Digital post-processing enabled low-frequency calibration of anechoic chambers. — Shows how 1/20-octave resolution digital acquisition made bass-region chamber correction feasible.
• Listening window averaging estimates the direct sound heard by a typical audience — Defines what the ‘listening window’ measurement concept is — the spatial average of off-axis direct sound.
• Low-frequency cutoff defined at −10 dB, not −3 dB, best predicts perceived fidelity. — Establishes why the conventional −3 dB half-power cutoff fails in small rooms, warranting a −10 dB definition for bass-extension correlation.
• Listener perception depends on sound power, direct sound, and reflections by frequency band — Establishes the operative framework that the three sound components (direct, first reflections, total power) each dominate different frequency regions.
• Total sound power is a spherical area-weighted sum over full orbitals around a speaker — Clarifies that total radiated sound power is defined as a spherical area-weighted sum of orbit measurements, with room absorption applied via reverberation-time data.
• Room standing waves dominate below the Schroeder frequency while the loudspeaker controls above it — Defines the Schroeder/transition frequency as the boundary where the room, not the loudspeaker, dominates the steady-state response.
• Spinorama measurement grew out of loudspeaker-room interaction studies — Names the spinorama as the measurement format that grew from this research lineage, giving context to the term.
• The science of acoustics began with concert hall reverberation theory — Establishes Sabine as the origin point of reverberation time as a concept, anchoring the whole tradition.
• Most popular-music recordings are built from close-miked or synthesized sounds, not live acoustic performances — Establishes that for popular music, the ‘performance’ is the mix heard over monitor speakers, a foundational definitional point for the whole book’s argument about sound reproduction.
• Listeners perceive the pitch of a bass note even when its fundamental is absent. — Defines the missing-fundamental phenomenon, a classic psychoacoustic case of the brain reconstructing pitch from harmonics.
• ITU and EBU listening tests differ fundamentally as relative versus absolute judgments. — Clarifies the distinction between relative (ITU) and absolute (EBU) listening evaluations—crucial for understanding why test setups differ.
• Professional control room designs range from dead to highly diffuse. — Defines the three main schools of control room acoustic design: non-room, live-end/dead-end, and all-diffuse.
• Cinema’s X-curve standard was based on primitive measurements that ignored better available research — Defines the X curve as the cinema target curve and explains its problematic origin.
• In-room measurement curves are dominated by reflections, not direct sound — Makes precise the conceptual distinction between a measured ‘result’ and an equalization ‘target’ — a key modeling concept.
• Blamed loudspeaker tweeter problems may actually originate in the recording microphone — Details the structural contrast between microphones and loudspeakers that underlies the whole argument.
• Modern studio mics are neutral transducers, while live mics trade neutrality for durability — Establishes what ‘neutral transducer’ means in the studio context and why live mics differ.
• Modern immersive audio delivers perceptual clues rather than reconstructing real sound fields — Clarifies the key distinction between sound-field capture (1930s) and modern ‘immersive’ clue-based reproduction.
• Head and torso simulators capture spatial cues with microphones at eardrum locations — Defines what a HATS (head and torso simulator) is and how it captures binaural cues.
• HRTFs are measured in anechoic space as angle-dependent transfer functions — Explains how HRTF data are formally measured and represented — amplitude/phase or impulse response per angle.
• Listeners perceptually normalize their own idiosyncratic HRTFs from birth — Clarifies HRTF normalization: the brain treats its own ear-specific transfer functions as uncolored baseline, regardless of how non-flat they physically are.
• Crosstalk cancellation delivers binaural separation through loudspeakers — Defines acoustical crosstalk cancellation as a means of delivering binaural information over loudspeakers to the sweet spot.
• Individualized HRTF data is required for reliable crosstalk cancellation — Explains how crosstalk cancellation works mechanically: matching HRTFs, tolerating head movements, and requiring dominant direct sound.
• Binaural hearing separates direct and reflected sound while monaural microphones cannot — Explains why single-point audience microphones produce overly reverberant recordings, a core psychoacoustics-of-recording insight.
• Toe-in loudspeaker aiming failed to stabilize phantom center imagery off-axis — Explains the Brittain toe-in arrangement and why time/intensity trading makes it only partially work, then fail entirely due to image breakup.
• Lateral wall reflections arrive attenuated by inverse-square law distances — Clarifies how off-axis loudspeaker curves approximate wall-reflection strengths (3.6 and 7.2 dB down) and the low-frequency truncation rationale.
• High broadband directivity reduces lateral reflection levels in loudspeakers — Illustrates the concept of broadband directivity and its measurable acoustic effect on reflections.
• Reflected sound anchors external source localization while its absence pulls sound into the head — Explains the mechanism by which missing reflections cause in-head localization, a key spatial-perception failure in psychoacoustics.
• Wide-dispersion loudspeakers soften hard-panned images and reduce the center-image crosstalk dip — Explains what ‘double-mono’ phantom center means and how wide dispersion helps stereophonic soundstages.
• Stereo and multichannel listening make listeners more forgiving of loudspeaker flaws — Overturns the common audio-forum assumption that stereo reveals more loudspeaker defects than mono.
• Off-center listeners lose the stereo illusion but retain musical content — Defines what the ‘sweet spot’ means practically and what happens when the listener moves out of it.
• Microphone-array and panned recordings obey the same interchannel amplitude and time rules. — Explains how spot microphones are integrated into stereo arrays and that the same IAD/ITD rules govern both approaches.
• Coincident and spaced microphone pairs encode direction into IAD or ITD cues. — Defines how stereo microphone techniques map to interchannel amplitude (IAD) and time (ITD) difference cues.
• The phantom center image in stereo is always corrupted at the symmetrical sweet spot — Defines phantom center image and clarifies why steady-state room curves don’t guarantee direct-sound matching.
• Facing forward corrupts center-image timbre due to head-related transfer function errors — Clearly attributes the audible timbre difference to HRTF encoding error, a core psychoacoustic mechanism.
• A transition frequency separates modal from ray acoustical behavior in rooms — Defines the Schroeder cross-over frequency fc = 2000·sqrt(T/V), the formal boundary between room modes and ray acoustics.
• Standing-wave thinking applies only at low frequencies in small rooms — Explains the meaning of the transition from modal (standing-wave) to ray-acoustical (reflection/interference) thinking as frequency rises.
• Small listening rooms lack diffuse reverberation and contain only early reflections — Clarifies why reverberation time is a misnomer for small rooms, distinguishing reflection decay time from resonance ringing time.
• Loudspeakers without annoying resonances tend to adapt well in real-world listening. — Defines what separates a saleable loudspeaker ‘personality’ from an audible defect: the absence of resonances makes a response easily adaptable.
• A mid-frequency off-axis sag is a common audible attribute of two-way loudspeakers. — Explains the ‘low-Q spectral hump between 2 and 6 kHz’ that results from sagging off-axis output — a perceptual artifact with a clear mechanical cause.
• Responsible listening tests use discriminant-selected programs and within-program comparisons — Spells out the design criteria (‘reveal differences, not disguise them’) and why repeated familiarization matters — a clear methodology definition.
• Small-room acoustics constrain bass quality below the Schroeder transition frequency. — Introduces the transition/Schroeder frequency as the boundary between two distinctive sound-field regimes.
• Low-Q resonances become audible at peaks below 0.5 dB in the midrange — Defines what Q-values (50, 10, 1) mean for resonance bandwidth and how they shift detection thresholds.
• Minimum-phase loudspeaker resonances are correctable with parametric equalization. — Defines what ‘minimum-phase’ and ‘invertible’ mean in the equalization context.
• Acoustical interference differs per off-axis angle and is averaged out perceptually in rooms — Clarifies the resonance-versus-interference distinction in measured curves.
• Blind tests show any equalization improves subjective loudspeaker ratings — Clarifies how equalizing the steady-state room curve only addresses low-Q resonances, since medium-Q ones are masked in the room average — a key psychoacoustic modeling distinction.
• Later-arriving reflections within the fusion zone do not create separate images. — Defines the fusion zone: later sounds suppressed for direction but still contributing loudness and quality, not masked.
• Reflections that appear as destructive comb filtering actually create perceived spaciousness. — Positions comb filtering as a monaural measurement artifact that binaural hearing reframes as spaciousness.
• Precedence fusion is not masking; all reflections remain audible — Sharpens what ‘fusion’ actually means in the precedence effect: spatial non-separation, not inaudibility.
• Perceptual changes detected at threshold become desirable when heard as image broadening — Defines apparent source width (ASW) as the positive translation of image spreading threshold.
• Humans are least sensitive to delayed sounds emerging from the same speaker — Connects the perceptual insensitivity to coincident delayed sounds with the comb-filtering phenomenon, clarifying why program-embedded comb filtering is least detectable even though it is characterized as most annoying.
• Fibrous absorbers become ineffective below roughly a quarter-wavelength thickness. — Pins down the quarter-wavelength rule that governs why thin fiber panels only absorb high frequencies.
• Reflection control reduces reflected energy either by absorption or by scattering. — Frames the two fundamental mechanisms (absorption vs. scattering) that organize all later reflection-control discussion.
• Elevation localization relies on pinnae spectral cues encoded as HRTFs — Defines HRTF via its physical origin in pinna folds and cavities.
• Elevation localization rests on spectral recognition of familiar sounds, not spatial cues. — Defines elevation localization as a timbral recognition task rather than a spatial one — a foundational conceptual distinction in psychoacoustics.
• Listeners prefer reverberation times of 1-1.1 s for piano in living-room-sized spaces — Gives concrete RT ranges (1-1.1 s preferred, 0.3-0.5 s typical furnished domestic) that anchor later psychoacoustic discussion.
• Reflections arriving from about 50-70 degrees lateral maximize perceived spaciousness. — Clarifies that 1 minus IACC (and 1 minus IACCE3) serves as a proxy for ASW/image-broadening preference.
• Perceived loudspeaker sound quality depends only on amplitude responses — Establishes which measurement domains actually drive perceived quality.
• Perceived quality is judged as deviation from an ideal amount. — Defines the defect-based perceptual evaluation framework Klippel used.
• True envelopment needs reflections delayed beyond 80 ms, impossible in small rooms alone — Sets the operational definition of true envelopment: requires reflections with delays >80 ms, which small-room acoustics cannot provide naturally.
• Frequency-dependent interaural cross-correlation measures sound-field reconstruction fidelity. — Defines FIACC as a tool for measuring how well a reproduced sound field matches the original across frequency.
• Matrixed quadraphonic crosstalk made localization unstable with head movement — Defines the core tradeoff of matrixed vs discrete multichannel: crosstalk leakage degrades separation and stability.
• Amplitude panning fails front-to-back because ear placement suits horizontal localization. — Explains why the quadraphonic array’s sweet spot is limited in both axes: physical ear geometry sets the constraint.
• Envelopment requires a center channel instead of a symmetric front-back array. — Defines ‘envelopment’ as the impression of being in a different acoustical space, the core objective of multichannel audio.
• Bipole but not dipole designs give surround channels needed coverage — Draws the working distinction between bipole (bidirectional in-phase) and dipole designs for surround use.
• Physically separated MTM drivers acoustically interfere off-axis because both radiate overlapping high frequencies — Explains the mechanism behind the MTM horizontal dispersion problem: two spaced drivers sharing a high-frequency crossover range cancel off-axis.
• THX dipole surrounds were bidirectional out-of-phase pairs, not true dipoles — Distinguishes the marketing-brand dipole surround from an acoustically true dipole (opposite-polarity surfaces with no separation).
• Constant beamwidth transducers deliver uniform sound levels over large areas — Introduces and defines the CBT (constant beamwidth transducer) concept.
• Cinema playback levels are calibrated with pink noise and C-weighting. — Explains the exact measurement protocol behind the SMPTE reference standard: pink noise, C-weighting, slow response.
• THX dipole surround speakers degraded direct sound while failing to create genuine diffusion. — Clarifies that diffusion is a property of a sound field, not a perception, and distinguishes bipole (in-phase) from incorrectly-named dipole (out-of-phase) configurations.
• Stereo upmixing quality varies because it depends on the pairing of recording and upmixer. — Explains why upmixing produces such varied judged results: it is always an interaction between an unpredictable recording technique and a specific upmixer algorithm.
• Renderers use metadata to adapt recordings to any loudspeaker configuration. — Defines what metadata does in downmixing/rendering pipelines.
• Most recordings are abstract constructions, not accurate reproductions of live music. — Sharpens what ‘high fidelity’ has come to mean versus its original intent — a useful framing for the whole field.
• The LFE channel was created to handle blockbuster bass beyond 40 Hz. — Explains the meaning and origin of ‘LFE’ (low-frequency enhancement/effects), clarifying why there is a separate subwoofer channel and its 40-120 Hz bandwith plus 10 dB headroom offset.
• Bass management reroutes low frequencies from small speakers to shared subwoofers. — Defines a core multichannel audio signal-processing term.
• Phantom imaging lets object-based audio create many locations from few loudspeakers — Explains how phantom images between loudspeaker pairs multiply effective localization positions in object-based audio.
• Room curves show loudspeaker results, not targets worth equalizing toward — Draws a sharp practical distinction between what a measured room curve means (outcome) and what it is not (a target to equalize toward).
• High-frequency loss with distance provides a perceptual cue for judging sound source distance — Explains the mechanism by which atmospheric absorption attenuates highs and how reverberant fields lose HF energy, a core psychoacoustic principle.
• Low frequencies produce tactile whole-body sensation while higher frequencies drive pitch perception — Clarifies the dual tonal-plus-vibratory perception operating in the bass region, distinguishing pitch cues from vibration cues.
• NC curves originated to rate speech intelligibility, not listener satisfaction — Clarifies what NC (Noise Criterion) curves actually measure and their original design purpose.
• Frequency response is the single most important measurable parameter of audio devices. — Defines frequency response as the amplitude vs. frequency curve and states its primacy among audio measurements.
• Nonlinear distortion adds frequencies that were not in the original signal — Defines nonlinear distortion by its defining property: generating new frequencies not in the input.
• High frequency resolution in waterfalls forces poor time resolution that misrepresents room decay. — Establishes the fundamental time-frequency resolution trade-off and how it manifests in waterfall measurements.
• Frequency and time domain representations equivalently define linear loudspeaker behavior — Clarifies the equivalence between frequency-domain (amplitude/phase) and time-domain (impulse response) descriptions of linear systems via Fourier transform.
• Music’s dense spectrum masks its own distortion products. — Explains why music is both the worst distortion generator and the best masker, a central psychoacoustic insight.
• A-weighted measurements ignore low-frequency energy that unweighted SPL captures. — Clarifies exactly when A-weighting and unweighted SPL diverge, which is a core conceptual distinction in psychoacoustic measurement.
• Upward masking makes intermodulation difference tones more audible than harmonics — Distinguishes harmonic distortion from intermodulation distortion, and explains why the two-tone test is more relevant at high frequencies.
• Audio distortion arises from level-dependent nonlinearity in the device’s transfer function — Defines nonlinear behavior in audio devices as the input-output relationship changing with level, and explains why distortion products appear as new sounds.
• Heating voice coils raises resistance and lowers transducer output — Drawing the precise distinction between power compression (a slowly varying linear distortion from coil heating) and non-linear distortion at excursion limits.
• Woofer excursion limits constrain dynamic range more than tweeter capabilities do — Clarifies the mechanism behind power compression and distortion onset at high levels.
• Subwoofers radiate omnidirectionally because their wavelengths far exceed diaphragm size — Pressure-source behavior: when wavelength is large relative to the source dimension, radiation is omnidirectional regardless of which way the diaphragm faces.
• Large cone diaphragms develop breakup resonances at high frequencies that color sound — Introduces the concept of diaphragm ‘breakup modes’ as a precise psychoacoustic phenomenon.
• Standing waves form when wavelengths match room dimensions — Precise definition of the mechanism behind room modes and standing waves.
• Large radiating surfaces become highly directional at high frequencies — Explains the wavelength-to-surface-size ratio that underlies loudspeaker directivity.
• Sound reflecting off a hard boundary has zero particle velocity — Establishes the complementary relationship between sound pressure and particle velocity at boundaries.
• Wall projections must exceed one-seventh wavelength to scatter sound usefully — Presents the 1/7-wavelength rule of thumb as a concrete design criterion for diffuser depth.
• Frequency response is the principal determinant of loudspeaker sound quality. — Defines frequency response as the central measured quantity in audio and its role as the main determinant of sound quality.
• Amplitude bumps in transducers imply predictable phase anomalies and time ringing. — Defines minimum-phase resonance behavior in transducer terms: amplitude bump implies phase anomaly and time ringing.
• Equal-loudness contours are a fixed property of human hearing — Defines what equal-loudness contours are and how they are measured, clarifying a core psychoacoustic concept.
• Screen fabric must lose under one dB yet remain porous enough to conceal speakers — Defines the practical transparency criterion for blind-test screens: under 1 dB on-axis transmission loss, achieved by tensioning the weave open.
• Head-tracking with measured impulse responses strongly improves sound externalization — Defines Binaural Room Scanning (BRS) and BRIR as technical terms.
• Constant errors normalize away in comparative loudspeaker tests — Clarifies why HRTF mismatch need not invalidate relative binaural loudspeaker comparisons.
• Subjective listening remains the final authority over measurement validity. — Clarifies that loudness balancing is signal-spectrum-dependent and that subjective tests verify measurements, not vice versa.
• Subjective sound quality is authoritative and measurements must explain it — Clarifies the correct role of measurement relative to subjective judgment in audio engineering.
• Familiar repeated test music reveals loudspeaker flaws that unfamiliar excerpts cannot — Explains the circle of confusion concept in the context of designing listening tests.
• Damping factor is the standardized specification for amplifier output impedance — Defines damping factor as the standardized way some manufacturers disclose output impedance.
• Most loudspeaker-wire mythology has no physical basis — Clarifies why transmission-line and skin-effect treatments of speaker wire are unrealistic at audio frequencies.
• Loudspeaker voicing is a guessing game born of poor engineer-consumer communication — Defines what ‘voicing’ means in the loudspeaker context, distinguishing it from musical voicing introduced in the prior paragraph.
• Naive and trained listeners agree closely on loudspeaker quality ratings — Establishes what ‘selection’ and ‘training’ of listeners means operationally and why it matters statistically.
• No single loudness meter can capture subjective loudness of varying program material across environments — Establishes the core challenge of loudness metering: signal non-stationarity compounded by listener-environment variability, the motivating problem for everything that follows in this chapter.
• The ITU loudness standard uses K-weighting with a 4 dB high-frequency head boost. — Clarifies the RLB/K-weighting origin and defines LKFS and LUFS metrics underpinning broadcast loudness normalization.
• Critics reject preference testing as mere taste, demanding realism or accuracy instead — Frames the long-standing objection to subjective preference testing in audio engineering as a clash between preference-based and fidelity-based criteria.
• Listener preference is driven mostly by timbral neutrality across the listening window — Plain-language definition of PIR as a weighted blend of listening window, early reflections, and sound power.
• The listening room, not the loudspeaker, determines perceived bass quality. — Clarifies the transition-frequency boundary between anechoic and room-dominated response.
• Home listening rooms show RT of 0.2–0.4 seconds with no diffuse field — Key contrast: domestic rooms lack a diffuse reverberant field, so RT measures something else entirely there.
• Concert halls need 1–2 seconds of reverberation balancing loudness against clarity — Defines RT60 precisely as time for a 60 dB amplitude reduction, with concrete typical values for performance venues.
• Statistical acoustics and classical critical distance do not apply in small rooms — States the boundary conditions under which classical room-acoustic modeling fails, a foundational scope restriction for the field.
• Near field and far field mislabel room zones better called direct versus reflected-sound dominant — Clarifies the competing uses of near-field/far-field in room acoustics versus source radiation contexts.
• A single steady-state room curve cannot represent what two ears and a brain perceive. — Explains why a steady-state room curve is a perceptual oversimplification — the microphone sums sounds that the ear/brain perceptually separates.
• Harman’s calibration target curve encoded deliberately tilted in-room response, not flat room response — Clarifies what the ‘Harman curve’ actually was: a tilted in-room target derived from knowing the anechoic loudspeaker response, meant to ensure a flat direct sound rather than a flat room curve.
• The Harman target curve applies only below the transition frequency. — Clarifies the scope of what the “Harman curve” actually targets — a common point of confusion in loudspeaker design.
• Cinema RT targets balance dialog clarity against realistic hall ambience. — Links mid-frequency RT range to dialog intelligibility and low-frequency RT to vocal formant amplification (chestiness) — the perceptual mechanism connecting a physical quantity to an audible artifact.
• Effective sound diffusers must be physically comparable in size to the waves they scatter — Explains why ornate opera boxes and statuary were acoustically useful — they were unplanned diffusers.
• Industry-internal sound translation may be arbitrary but public translation cannot be — Frames the technical meaning of ‘translating’ sound between a mixing stage and an audience — a key control-room design concept this book returns to.
• Excessive absorption can degrade speech intelligibility — Names and defines the early reflection benefit (ERB) figure of merit.
• Deep broadband diffusers can create a 30 dB immediate reflection drop — Introduces the ‘Ambechoic’ concept — a useful term for describing a room that combines anechoic early drop with dense dispersed reflections.
• A room can sound anechoic and reverberant simultaneously — Clarifies that ‘anechoic-sounding’ is a perceptual property independent of actual reverberation presence.
• Carpet underlay type determines whether flooring absorbs sound at all — Clarifies that felt, not foam/rubber, is what makes underlay acoustically fibrous.
• Diffusers mainly attenuate specific reflections rather than create diffuse fields — Reframes the purpose of diffusers in listening rooms: targeted reflection attenuation rather than genuine diffusion.
• Diffusion terminology is routinely misapplied to small rooms — Clarifies the terminological distinction between diffusers/scatterers and true diffuse fields, and why ‘diffusion’ is inapplicable in small absorptive rooms.
• Perfect diffusion is an unattainable ideal in real rooms — Defines diffusion precisely as isotropic plus homogeneous, and notes the practical limit in reverberation chambers.
• In rooms the inverse-square law applies only to the direct sound — Clarifies the point-source abstraction and precisely scopes when the inverse-square law holds.
• Far field onset distances vary widely by source size and wavelength — Defines the engineering rule of thumb for where far-field conditions (and thus valid anechoic measurements) begin.
• Common tall loudspeakers are not true line sources — Defines ‘true line source’ against the common multiway tall loudspeaker, setting up why truncated line sources degrade.
• Tall speakers with stacked woofers are not true line arrays — Sharply distinguishes marketing jargon ‘line source/array’ from the actual acoustical definition of the term.
• Curved, Legendre-shaded line arrays exploit floor reflections to maintain constant beamwidth at all frequencies — Names and characterizes the Constant Beamwidth Transducer (CBT) as a curved, shaded line source whose floor image extends the array.
• Boundary reflections create acoustical images that halve the radiation solid angle — Defines solid angle (steradians) and the acoustical-image model of boundary reflections in precise quantitative terms.
• Boundary-image relationships hold only when wavelengths exceed source size and separation — States the wavelength-and-geometry validity condition that limits the classic image model.
• Boundary placement boosts low-frequency output by 6 dB per solid-angle halving. — The ‘Allison effect’ gets its named definition here: the 6 dB-per-8π-halving gain from adjacent boundaries, limited by quarter-wavelength spacing.
• Adjacent boundaries alter radiated sound power via acoustical radiation resistance — Identifies acoustical radiation resistance as the mechanism by which boundary proximity changes radiated sound power — a core psychoacoustic modeling term.
• Smaller drivers radiate more omnidirectionally at a wider frequency range — Defines directivity index as the difference between on-axis and sound-power responses, with 0 dB meaning omnidirectional.
• Conventional and bookshelf loudspeakers are engineered for free-standing placement — Clarifies what ‘bookshelf loudspeaker’ means in practice versus design intent - the term is misleading since they’re optimized for free-standing use.
• Wall mounting creates a comb-filter cancellation dip whose frequency scales with baffle size. — Concrete instance of a comb filter’s first destructive-interference tooth tied to a specific physical dimension.
• Flush-mounting in a wall boosts bass output of a loudspeaker not designed for it. — Defines the ‘hinge’ frequency concept — the frequency below which wall-mounting raises output, here around 500 Hz.
• Greater loudspeaker-wall separation shifts the adjacent-boundary dip to lower frequencies — Defines the adjacent-boundary effect mechanism: distance from wall determines the dip frequency, directivity determines its bandwidth.
• Soffit mounting in control rooms is a non-optimal corruption of half-space mounting — Explains that ‘soffit mounting’ in audio is a corruption of half-space mounting, with the word normally meaning something else.
• Bipole surround loudspeakers radiate hemispherically to deliver similar direct sound to all listeners — Defines bipole (bidirectional in-phase) radiation and contrasts it with dipole versions for immersive systems.
• Bass performance drives roughly 30% of overall loudspeaker sound-quality ratings. — Quantifies just how much weight low-frequency performance carries in overall subjective sound-quality ratings.
• Axial room modes can be predicted from room dimensions alone — A concrete, worked example of how to compute axial standing-wave frequencies from room dimensions.
• Waterfall measurements reveal no information beyond what frequency response curves provide. — Introduces the minimum-phase property of room resonances, a key psychoacoustic concept linking frequency and time domains.
• Two subwoofers in opposite mode lobes can cancel room resonances without equalization — Concretely illustrates how modal coupling factor cancellation works in practice for two room modes simultaneously.
• Mode cancellation neutralizes modes for the listening system but not the physical room — Draws the important distinction between physical room modes and their coupling to the playback system — a conceptual framing that clarifies what mode cancelling actually accomplishes.
• MSV, MOL, and VSA are the formal metrics for evaluating multi-subwoofer bass. — Defines the three key objective metrics (MSV, MOL, VSA) for evaluating low-frequency spatial performance.
• Design priorities determine which subwoofer-seating configuration optimizes a room. — Names the three key optimization metrics—MOL, MSV, VSA—by their design priorities.
• Delayed, inverted subwoofer arrays can cancel standing waves in rectangular rooms — Explains the double bass array (DBA) mechanism: a plane wave generated at the front wall is cancelled at the rear by a delayed, polarity-inverted array.
• Multiple identical subwoofers reduce seat-to-seat bass variation — Defines MSV (mean spatial variance) and VSA as the two key metrics, and gives calibration values for what counts as noticeable (25%) vs. game-changing (50%) improvement.
• Subwoofer arrays can be time-aligned and equalized to minimize seat-to-seat bass variation — Explains how Harman’s Sound Field Management actually works: superposition, gain/delay/EQ manipulation with constrained parameters, and brute-force optimization.
• High-resolution measurement and matched Q are required for effective modal EQ. — Explains why 1/20-octave resolution and Q-matching matter, and why graphic EQs fail — a precise practical mechanism.
• Modal frequency resonance is position-independent while coupling is position-dependent — Clarifies the key separation in modal analysis: frequency resonance is universal to a mode, while source/receiver coupling varies with position.
• Rectangular rooms allow predicting low-frequency modal behavior in advance — Establishes why rectangular room geometry is the design default — it makes low-frequency fields computationally tractable.
• Room modes being minimum-phase means fixing the spectral bump also fixes the ringing — Stakes out the minimum-phase property of low-frequency room resonances, the key theoretical justification for why equalization reduces both magnitude bump and time-domain ringing.
• Resonance Q factors below about 16 are subjectively imperceptible to listeners. — Q factor here equals resonance sharpness; gives concrete audible-imperceptibility thresholds per frequency.
• Simultaneous subwoofer outputs cannot be predicted from individually measured responses — Clarifies why transfer function (amplitude+phase) measurements are needed rather than steady-state amplitude responses for predictable acoustical summation.
• Room pressurization is a compliance effect that fades in unsealed rooms — Clarifies the 0,0,0 mode as room pressurization/room gain, a first-order compliance effect below the first axial mode.
• Reducing energy in a single problem mode lowers seat-to-seat response variance. — Explains the core mechanism by which modal manipulation reduces seat-to-seat variance.
• Non-parallel walls do not eliminate room modes — Clarifies that room modes arise from the enclosure and source/absorption distribution, not wall parallelism; a common studio-design myth is corrected here.
• Adding absorption reduces seat-to-seat bass variation significantly — Clarifies that damping reduces modal Q, widening peaks rather than just lowering them.
• Positional equalization finds seating spots weakly coupled to resonances — Introduces the term ‘positional equalization’ and defines it precisely.
• Powered subwoofer hardware can be repurposed as active bass absorbers — Clarifies what an active bass absorber is versus a powered subwoofer.
• Narrow-band tuned absorbers target specific modes while broadband traps address many — Distinguishes narrow-band tuned membrane absorbers from broadband absorbers.
• Headphone reproduction lacks the spatial cues loudspeakers in rooms provide — Establishes the fundamental premise that stereo mixes target room playback, not headphone playback — a grounding definitional point.
• Ear-tip insertion depth shifts canal resonance upward by several kilohertz — Clarifies how insertion depth physically alters the ear canal’s effective acoustics and resonance.
• Pinna geometry alone changes headphone measurements through leakage — Clarifies how pinna-generated leakage shifts low-frequency headphone response independently of the coupler.
• Coupler type 4.3 shifts both low and high frequency headphone readings — Explains the Type 3.3 vs Type 4.3 ear simulator distinction through its measurable consequences.
• ANC and PNC headphone performance is standardized as insertion loss measured with pink noise. — Defines the IEC 60628-24 measurement standard and the insertion-loss metric for ANC/PNC headphones.
• Headphone target curves can be derived computationally from HRTFs without a physical reference field. — Defines HRTFs precisely: transfer functions (frequency and phase) at the blocked ear canal, capturing ITD, IID, and spectral localization cues.
• Binaural recordings capture nonlinear headphone distortions; virtual methods do not — Clarifies what each headphone evaluation method captures — linear vs. nonlinear distortion.
• Headphones lack the phantom-center timbre notch because no interaural crosstalk exists. — Explains why the 2 kHz phantom-center notch is a loudspeaker-only artifact absent in headphone listening.
• Headphone target measurement averages six manikin positions across three angles — Clarifies the standard measurement protocol behind the Harman headphone target — averaging 2 ears over 3 angles.
• A shared loudspeaker and headphone target curve solves the Circle of Confusion — Defines ‘good translation’ — a recording sounding similar across loudspeaker and headphone — and links it to the Circle of Confusion concept.
• Ear simulator corrections depend on the headphone’s own acoustic load — Explains the mechanism by which ear-simulator differences interact with headphone acoustic impedance.
• Room reflections aid resonance audibility that headphones must control internally — Clarifies how Q of resonances and room reflections interact differently between loudspeaker and headphone reproduction—a core psychoacoustic distinction.
• A flat steady-state in-room response boosts high-frequency direct sound — Illustrates the steady-state vs direct-sound distinction: flattening in-room steady state skews the direct field bright above 2-3 kHz.
• Binaural room impulse responses generate spatial audio via convolution — Explains how BRIRs create spatial content: convolving stereo tracks with individual head-related impulse responses.
• Listener-preferred headphone response mirrors a neutral loudspeaker’s in-room response — Defines PIR (predicted in-room response) and explains why headphones targeting it sound best.
• Personalized HRTFs enable elevated externalized spatial audio over headphones — Defines HRTFs and what they encode (interaural time/level differences and spectral cues).
• Some listeners reject headphones due to in-head localization and lack of bass tactility — Defines in-head localization — the key perceptual shortcoming of headphone reproduction vs. loudspeakers.
• Test fixture fidelity to human measurements remains an open question — Establishes the core principle of artificial-head test fixtures: coupling fidelity drives correlation between measured and heard sound.
• Cochlear damage produces distinct perceptual deficits depending on which cell type is affected — Defines loudness recruitment — a more rapid than normal growth of loudness with increasing sound level.
• Custom musicians’ earplugs reduce volume without destroying timbre — Introduces what musicians’ earplugs are and why flat (timbre-preserving) attenuation matters.
• Hearing loss impairs spatial sound separation, not just frequency detection. — Defines Spatial Release from Masking (SRM) and connects it to soundstage image separation in immersive audio.
• Audiometrically normal listeners may still have substantial hidden hearing loss — Introduces ‘hidden hearing loss’ as a concept distinct from standard audiometric impairment.
• Listener ‘clarity’ ratings correlate with intelligibility but are not a direct measure — Distinguishes the perceptual impression of ‘clarity’ from the quantitative measure of intelligibility.
• Bass rise in reflected sound is physically unavoidable with forward-firing speakers. — Clarifies why a tilted steady-state room curve is natural rather than a defect — directional-energy, reverberation, and air attenuation all conspire toward it.
• The direct, on-axis sound dominates perceived loudspeaker quality in rooms. — Defines the conceptual distinction between room curves (results) and direct sound (target) that anchors the whole chapter.
• Resonance-free response and flat direct sound define timbral neutrality — Distinguishes resonances (angle-independent) from interference dips (angle-dependent) — key physical mechanism for identifying resonant loudspeakers from polar measurements.
• Speaker break-in effects are listener adaptation, not hardware change — Clarifies ‘breaking in’ as a perceptual adaptation phenomenon rather than a physical component change.