The ear’s frequency response is level-dependent, favoring mid frequencies at low volume

Evidence

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 (#expands, via linked claim)

Categorization

• XREF: connects to: The ear becomes less nonlinear as sound levels rise; Human hearing requires far more SPL to detect low-frequency tones than mid-range ones; Outer and middle ear transfer function determines loudness across frequency. (+7 more)

Broader Connections

• Ear frequency response varies with amplitude, especially at low frequencies. #corroborates (0.95)
• Pitch correlates with frequency but is also slightly level-dependent #expands (0.80)
• Auditory filters respond asymmetrically, favoring frequencies below center #expands (0.78) — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1124
• Cochlear frequency selectivity decreases as sound level increases #complicates (0.70)