Frequency dependence of acoustic distortion products in a locally active model of the cochlea.

In two-tone experiments it has been shown that acoustic distortion products are "tuned" as a function of primary frequency ratio, that is, at a certain frequency ratio a maximum in emission occurs. Several authors maintain that this "tuning" is caused by band-pass filtering of the distortion products as they are coupled back to the basilar membrane. In this paper one possible other cause for this type of tuning is brought to light. It is shown that the same kind of "tuning" is present in a locally active cochlea model without such a filtering of distortion products. In this view "tuning" becomes evident because, when the frequency ratio is near unity, the primary components tend to suppress one another, and suppress the DP, too.