Basilar membrane displacement produces an asymmetric filter response across frequency.

Evidence

As the input pure tone is raised to Fc Hz, the membrane displacement gradually increases with the less steep side of the displacement curve. As the frequency is increased above Fc Hz, the membrane displacement falls rapidly with the steeper side of the displacement curve. This results in the filter response curve as shown, which is an exact mirror image about Fc Hz of the basilar membrane displacement curve. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 593

The filter response curve is plotted by observing the basilar membrane displace­ ment at the place corresponding to Fc Hz for each input pure tone and plotting this as the filter response at the frequency of the pure tone. This results in the response curve shape illustrated as follows. — David Howard, Jamie Angus, coustics and Psychoacoustics, 573

Categorization

• DEFINE: Explains why the cochlea’s filter curves are asymmetric — gradual rise, steep drop.
• corroborated: 5 independent passages support this claim — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 593; David Howard, Jamie Angus, coustics and Psychoacoustics, 573
• XREF: connects to: Broad-spectrum sounds read as louder because auditory bands integrate across the basilar membrane; Basilar membrane stiffness gradients create a frequency-to-place mapping; Gammatone filters match the auditory nerve’s measured impulse response (+5 more)

Broader Connections

• Auditory filters respond asymmetrically, favoring frequencies below center #expands (0.85) — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1124