A compressive gammachirp auditory filter for both physiological and psychophysical data.

Area of Science:

• Auditory Neuroscience
• Psychoacoustics
• Signal Processing

Background:

• The analytical gammachirp filter, a level-dependent auditory filter, was developed to explain psychophysical masking data.
• This filter did not explicitly represent changes in filter gain or compression with sound level.

Purpose of the Study:

• To review the analytical gammachirp filter's architecture in relation to cochlear physiology.
• To introduce a new compressive gammachirp filter where gain and compression vary with level, but the chirp does not.

Main Methods:

• Reviewed the architecture of the analytical gammachirp filter.
• Described a new compressive gammachirp filter model.
• Fitted the new filter to existing psychophysical data (reverse-correlation and masking).

Main Results:

• The analytical gammachirp filter's limitations in representing level-dependent cochlear filtering were identified.
• The new compressive gammachirp filter successfully fits level-dependent reverse-correlation and masking data.
• The chirp in the new filter does not vary with sound level.

Conclusions:

• The compressive gammachirp filter provides a more physiologically plausible and empirically supported model of auditory filtering.
• This model better explains how the cochlea processes sound at different intensity levels.