Phenomenological model for two-tone suppression

A model relating discharge rate in single auditory-nerve fibers to parameters of a two-tone stimulus is presented. We consider cases where one tone is at fiber characteristic frequency (CF) and the other tone produces two-tone suppression. The last stage in the model is a saturating nonlinearity. For the CF tone presented alone, the input to this nonlinearity is the CF amplitude; in the two-tone case, the CF amplitude is attenuated by a factor which depends only on the suppressor-tone amplitude and frequency. The model serves to relate a number of two-tone studies. In particular, it predicts our recently reported differences in two-tone suppression for the cases of suppressor frequencies above and below fiber CF.