2-TONE SUPPRESSION IN A LOCALLY ACTIVE NONLINEAR MODEL OF THE COCHLEA

In auditory nerve, inner-hair cell and basilar-membrane responses, it has been found that the response to one tone can be suppressed by anot her tone. This phenomenon, called two-tone suppression, is examined on the level of the basilar membrane with a locally active long-wave mod el of the cochlea in which the active mechanism is nonlinear. The mode l is solved in the frequency domain by means of a quasilinear solution method. Several phenomena, such as difference in growth of suppressio n for low-side and high-side suppressors and critical dependence of th e phase of the probe response on suppressor parameters, have been repl icated. The attenuation hypothesis which states that the presence of a suppressor has the same effect on the probe response as attenuation o f probe level is shown to be insufficient in explaining the experiment al data. This model, in which suppression is simply reduction of power amplification due to saturation of the active mechanism, is more succ essful in this respect.