Multifrequency Forcing of a Hopf Oscillator Model of the Inner Ear

¹ University of Utah

^* To whom correspondence should be addressed. E-mail: kmontgom24{at}yahoo.com.

Submitted on July 31, 2007
Revised on October 1, 2007
Accepted on 18 March 2008

	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 non-interacting 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.

Key Words: Hair Cells, Hopf Bifurcation, Inner Ear, Otoacoustic Emissions