Broadband ETCs are untrustworthy whenever reflections differ spectrally from direct sound
Evidence
All of this is especially relevant in room acoustics because acoustical materials, absorbers and diffusers, routinely modify the spectra of reflected sounds. Whenever the direct and reflected sounds have different spectra simple broadband ETCs or impulse responses are not trustworthy indicators of audible effects. — Toole, Floyd E, Sound reproduction- the acoustics and…, 678
Categorization
Category: Causal Relationships
Related
- Acoustical materials alter reflection spectra, invalidating broadband measurements for audibility (similarity 0.89)
- Room reflections cannot be corrected by electronic equalization (similarity 0.83)
- Random-incidence absorption coefficients fail to predict actual reflected spectra (similarity 0.82)
- Time-domain reflection displays conceal spectral content and mislead comparison (similarity 0.82)
- ETC displays can misreport reflection levels by about 20 dB versus audibility (similarity 0.82)
- Loudspeaker quality depends on off-axis radiation because rooms reflect it (similarity 0.82)
- High broadband directivity reduces lateral reflection levels in loudspeakers (similarity 0.81)
- EQ cannot fix directivity problems that a better loudspeaker requires (similarity 0.81)
- Room reflectivity at low frequencies determines bass elevation in measured steady-state curves (similarity 0.81)
- Resonances are the primary problem in loudspeakers (similarity 0.81)
- Early lateral reflections are attenuated by loudspeaker directivity, not harmful. (similarity 0.80)
- ETC spike heights correlate inversely with actual audibility of reflections (similarity 0.80)
- Reflected sound waves interfere with direct waves to create frequency peaks and dips (similarity 0.80)
- Loudspeakers and rooms act as a combined system that cannot be judged separately (similarity 0.80)
- On-axis response alone cannot predict how a loudspeaker sounds in a room (similarity 0.80)
Broader Connections
- Room reflections cannot be corrected by electronic equalization
#expands(0.85) — Toole, Floyd E, Sound reproduction- the acoustics and…, 122 - Audible effects of reflections require spectral comparison across time-domain spikes
#expands(0.85) — Toole, Floyd E, Sound reproduction- the acoustics and…, 677 - Early reflection control often concealed flawed off-axis loudspeaker performance.
#exemplifies(0.80) — Toole, Floyd E, Sound reproduction- the acoustics and…, 339 - Acoustic impedance mismatch determines both reflection phase and magnitude
#contradicts(0.75) — David Howard, Jamie Angus, coustics and Psychoacoustics, 353