The loudness function approaches a vertical asymptote at the 3 dB threshold in quiet

Evidence

This influence of threshold in quiet becomes clear when the curves outlined in Fig. 8.17 are used. For large excitation level, L E , the same specific loudness is reached independent of the threshold in quiet. For lower levels, however, the influence of threshold in quiet becomes very strong as the excitation level approaches the level given as the parameter. This means that the influence of threshold in quiet is most prominent for relatively faint sounds. Another effect also becomes visible: the influence of threshold in quiet, which is often assumed to play an important role, is smaller than expected for medium and high levels. The reason for this is that the three octaves between 20 and 160 Hz, within which the threshold in quiet changes drastically when plotted as a function of frequency, are reduced to the relatively small value of only 1.5 Bark if plotted as a function of critical-band rate. Therefore, the influence of threshold in quiet is usually effective in everyday loudness calculation only at the left end of the loudness distribution. — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1281 (#corroborates, via linked claim)

Loudness is the perceptual correlate of sound level. But it is also dependent on frequency, incident angle, the duration of the signal and its temporal envelope. It is one of many psychoacoustic relationships that defy simple descriptions. Yet, one must start somewhere, and so most investigators focused on pure tones in acoustically simple circumstances, like headphone or anechoic listening. — Toole, Floyd E, Sound reproduction- the acoustics and…, 903 (#expands, via linked claim)

Loudness is mainly the perceptual correlate of sound intensity, which is usually expressed in dB SPL as sound pressure level on a logarithmic scale. However, loudness judgments are also affected by several other variables, including physical sound parameters like e.g. duration, spectral content and temporal modulation as well many more acoustic and non-acoustic factors, including the particular task or context and personal factors like the individual hearing status (Florentine et al. — Dijk, Pim van, Physiology, Psychoacoustics and…, 2610 (#expands, via linked claim)

Categorization

• XREF: connects to: Threshold in quiet affects loudness mainly for faint sounds — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1281; Loudness depends on more than physical sound intensity alone — Dijk, Pim van, Physiology, Psychoacoustics and…, 2610; Loudness depends on frequency, angle, duration, and envelope, not just level — Toole, Floyd E, Sound reproduction- the acoustics and…, 903

Related

• Threshold in quiet affects loudness mainly for faint sounds (similarity 0.95)
• Loudness depends on frequency, angle, duration, and envelope, not just level (similarity 0.90)
• Loudness depends on more than physical sound intensity alone (similarity 0.90)
• Loudness falls to zero at threshold in quiet, forcing a vertical asymptote (similarity 0.88)
• Loudness scales with frequency squared, requiring large amplitude at low frequencies (similarity 0.87)
• Low-frequency loudness growth compresses as level rises (similarity 0.85)
• Loudness is perceptual and unmeasurable directly, while intensity is acoustic and directly quantifiable (similarity 0.85)
• Threshold in quiet depends on total sound intensity within one critical band only (similarity 0.85)
• The threshold in quiet is highly reproducible for individual subjects (similarity 0.85)
• Loudness, measured in sones, depends inherently on frequency content (similarity 0.84)
• Sound intensity level and sound pressure level are roughly equivalent (similarity 0.84)
• Loudness perception is essentially logarithmic (similarity 0.84)
• Auditory threshold for broadband noise is set by the most sensitive frequency region only (similarity 0.84)
• Loudness grows with bandwidth via area tradeoff except at extreme levels (similarity 0.84)
• Loudness is not reducible to sound pressure level or signal power (similarity 0.84)

Broader Connections

• Threshold in quiet affects loudness mainly for faint sounds #corroborates (0.80) — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1281
• Loudness depends on frequency, angle, duration, and envelope, not just level #expands (0.78) — Toole, Floyd E, Sound reproduction- the acoustics and…, 903
• Loudness depends on more than physical sound intensity alone #expands (0.75) — Dijk, Pim van, Physiology, Psychoacoustics and…, 2610