Hearing becomes less sensitive to frequency variations as level increases

Evidence

This means that our hearing system becomes — in contrast to our expectation - less sensitive to cut-off frequency variations at higher levels. Normally, we think that we can hear better if we increase the level. This unexpected behaviour is understandable in terms of the model. The upper slope becomes flatter and flatter with increasing level; it decreases from about 30 dB/Bark at low level to about 5 dB/Bark at high levels near 100 dB. This decrement of the slope corresponds to the rise in 211f from about 40 Hz at 30 dB to about 240 Hz with the low-pass noise at a level of 100 dB. — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1148

Categorization

• QUESTION: Why does the excitation-pattern upper slope flatten with level? The model explains it mechanistically, but the perceptual consequence (hearing gets worse at higher levels) is worth chasing further.