Computational modeling of distortion product otoacoustic emissions

Otoacoustic emissions are sounds generated by the cochlea that can be measured in the ear canal. Distortion product otoacoustic emissions (DPOAEs) are generated when the cochlea is stimulated by two primary tones and are a result of nonlinearities within the outer hair cells of the cochlea. DPOAEs are commonly used clinically to determine the health of the inner ear and scientifically to obtain noninvasive data about cochlear function. A physiologically based computational model of the mammalian ear is used to study the generation of DPOAEs. This model includes a nonlinear model of the cochlea, formulated in the time-domain and based on the finite element method and a lumped parameter model of the middle ear. Model simulations for the basilar membrane displacement, intracochlear fluid pressure, and ear canal pressure at the distortion product frequency in response to a two-tone stimulus are compared with experimental data and other modeling studies. The effects of various primary frequencies and input signal levels on the generation of DPOAEs are studied.