A composite model of the auditory periphery for simulating responses to complex sounds.

Abstract

This paper presents a phenomenological model of the cochlea. It consists of a bank of nonlinear time-varying parallel filters and an active distributed feedback. Realistic filter shapes are obtained with the all-pole gamma-tone filter (APGF), which provides both a good approximation of the far more complex wave propagation or cochlear mechanics models and a very simple implementation. Special care has been taken in modeling nonlinear properties in order to mimic the responses of the cochlea to complex stimuli. As a result, the model reproduces several observed phenomena including compression, two-tone suppression, and suppression of tones by noise. The distributed feedback, based on physiological evidence from outer hair cell (OHC) functioning, controls the damping parameter of the APGF and provides good modeling of both low-side and high-side suppression. Responses to more complex stimuli as well as a study of the model's parameters are also presented. Areas of application of this type of model include understanding of signal coding in the cochlea and auditory nerve, development of hearing aids, speech analysis, as well as input to neural models of higher auditory centers.