A study on the input-output function of a nonlinear cochlear transmission-line model with the function of an outer hair cell model

A nonlinear cochlear transmission-line model with the physiological function of an outer hair cell (OHC) model is presented to investigate how OHCs produce the nonlinearity in the input-output (IO) functions of cochlear filtering. As the physiological function of the OHC model, the pressure produced by the somatic motility of the OHCs was studied. The somatic motility is induced by the transducer currents that change with the displacement of the hair bundle. The pressure produced by the OHC model can be linearly approximated by the amount of current. The proposed model is comprised of a middle ear model and a cochlear transmission-line model, which includes a basilar membrane and lymph fluid model, a tectorial membrane model, hair bundles model, and the OHC model. The model’s parameters were set as estimates for a human obtained from animal data. In simulation results, this model could account for the IO functions of cochlear filtering obtained from both physiological and psychological experiments. These results suggest that the somatic motility of the OHCs, which depends on the transducer currents, produces the nonlinearity in the IO functions of cochlear filtering.