Increasing stimulus level broadens auditory filters and causes upward spread of masking

Evidence

More subtly, it is possible for speech that is produced at high levels to mask itself. That is, if the speech is too loud, then, notwithstanding the improvement in signal-to-noise ratio, the intelligibility is reduced, because the low-frequency components of the speech mask the high-frequency components due to the upward spread of masking. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2480 (#expands, via linked claim)

The second important factor in such systems is the frequency resolution. We have seen that the critical bands provide a good first approximation for frequency resolution. Actually, slopes of critical-band filters are not infinitely steep but finite, and can be approximated by the steepness of 27 dB/Bark towards low critical-band rates (low frequencies). Towards larger criticalband rates (higher frequencies), the slope depends on level and decreases with increasing level from about 27 dB/Bark to 5 dB/Bark over the 60-dB range above 40 dB. In total, the frequency selectivity of our hearing system can be approximated by the excitation level versus critical-band rate pattern. — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1124 (#corroborates, via linked claim)

When two or more pure tones are heard together an effect known as “masking” can occur, where each individual tone can become more diffi­ cult or impossible to perceive, or it is partially or completely “masked,” due to the presence of another tone. In such a case the tone which causes the masking is known as the “masker” and the tone which is masked is known as the “maskee.” These tones could be individual pure tones, but, given the rarity of such sounds in music, they are more likely to be individual fre­ quency components of a note played on one instrument which mask either other components in that note, or frequency components of another note. — David Howard, Jamie Angus, coustics and Psychoacoustics, 1628 (#exemplifies, via linked claim)

Categorization

• XREF: connects to: Masked tones recover pitch strength as their level rises above masked threshold — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 850; Masking spreads from a noise band to tones further away as masker level rises; A masker raises the audibility threshold of a test sound. (+8 more)

Broader Connections

• Loud speech can mask its own high-frequency components via upward spread of masking #expands (0.95) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2480
• Auditory filters respond asymmetrically, favoring frequencies below center #corroborates (0.85) — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1124
• Simultaneous tones become harder to perceive due to masking effects #exemplifies (0.80) — David Howard, Jamie Angus, coustics and Psychoacoustics, 1628
• Masking acts within critical bandwidths, leaving distant-frequency sounds unaffected #qualifies (0.80) — Eric J. Heller, Why You Hear What You Hear- An…, 2009