Spontaneous oto-acoustic emissions in lizards: non-linear models and the effect of coupling

Spontaneous Otoacoustic Emissions in the tokay geko: Nonlinear Models and the Effect of Coupling The hearing of tetrapods, including humans, is enhanced by an active process that amplifies the mechanical responses to sound, sharpens frequency discrimination, and compresses the range of intensity responsiveness. The most striking manifestation of such active process are spontaneous otoacoustic emissions, the unprovoked emergence of sound from an ear. Hair cells, the sensory receptors of the inner ear, are known to provide the energy for such emissions; it is unclear, though, how ensembles of such cells collude to power observable emissions. In this paper we will present measures and models of spontaneous otoacoustic emissions from the ear of the tokay gecko, a convenient experimental subject that produces robust emissions. Our results suggest that elastic coupling between oscillators, modelled as cluster of hair cells within a tonotopic array, explains several properties of the spontaneous otoacoustic emissions in the gecko.