A mechanical-electrical-acoustic model of the cochlea

The coupling of the mechanical and the electrical response of the cochlea is well known. Acoustical stimulation gives rise to the cochlear microphonic while electrical stimulation of the cochlea elicits both basilar membrane motion and otoacoustic emissions. Disruption of the resting electrical environment, through efferent stimulation, artificial injection of current, and a variety of other means is known to affect hearing sensitivity and the mechanical response of the cochlea to stimulus. The key missing element in most models is the explicit coupling of the electrical domain to the mechanical degrees of freedom. By modeling this coupling, predictions of both mechanical forces and transducer currents may be made enabling comparisons and analysis of electro-physiological experiments. A mechanical-electrical-acoustic model of the cochlea is presented whose key components are micro-electro-mechanical coupling of the cochlear structures, a two-duct acoustic model with structural-acoustic coupling at the basilar membrane (BM), and a global electrical circuit to model conductances in the different scalae. Predictions of the cochlear microphonic, other cochlear potentials, BM velocity and otoacoustic emissions in response to pure acoustic input and bipolar electrical stimulation are presented. Model simulations show that including three dimensional fluid effects improves BM response characteristics. A tectorial membrane shear mode resonance is shown to provide amplification to the BM at the characteristic frequency of a location. This project is funded by NIH NIDCD R01-04084.