Response suppression and transient behavior in a nonlinear active cochlear model with feed-forward

A nonlinear active cochlear model is used to simulate the steady-state frequency response and transient response to clicks of the basilar membrane. The model includes the three-dimensional viscous fluid effects, an orthotropic cochlear partition with dimensional and material property variation along its length, and a nonlinear active feed-forward mechanism to represent the activity of the outer hair cells. A hybrid asymptotic and numerical method is used to provide a fast and efficient iterative procedure for modeling and simulation of the nonlinear responses in the active cochlea. The simulation results exhibit some of the characteristic nonlinear behavior of the basilar membrane commonly observed in experimental measurements, such as significant amplification and sustained "ringing" in the transient response at low stimulus level. The simple feed-forward mechanism is able to capture the properties of the noncausal active process in the cochlea without a second filter or resonance.