Multifrequency Forcing of a Hopf Oscillator Model of the Inner Ear

TL;DR

This paper models the inner ear's otoacoustic emissions using an array of noninteracting Hopf oscillators tuned at different frequencies, explaining experimental results and differences between mammals and nonmammals.

Contribution

It introduces a novel Hopf oscillator model to predict otoacoustic emissions and explains interspecies differences in auditory processing.

Findings

Model accurately predicts three-frequency suppression experiments.

Supports active hair cell motion as key to sound processing.

Provides insights into mammalian and nonmammalian auditory differences.

Abstract

In response to a sound stimulus, the inner ear emits sounds called otoacoustic emissions. While the exact mechanism for the production of otoacoustic emissions is not known, active motion of individual hair cells is thought to play a role. Two possible sources for otoacoustic emissions, both localized within individual hair cells, include somatic motility and hair bundle motility. Because physiological models of each of these systems are thought to be poised near a Hopf bifurcation, the dynamics of each can be described by the normal form for a system near a Hopf bifurcation. Here we demonstrate that experimental results from three-frequency suppression experiments can be predicted based on the response of an array of noninteracting Hopf oscillators tuned at different frequencies. This supports the idea that active motion of individual hair cells contributes to active processing of sounds in the ear. Interestingly, the model suggests an explanation for differing results recorded in mammals and nonmammals.