Interactions among spontaneous otoacoustic emissions. I. Distortion products and linked emissions.

Spontaneous otoacoustic emissions (SOAEs) can be recorded from human ears with a sensitive microphone in the ear canal. The evidence to date strongly indicates that the origin of these emissions in an active electro-mechanical process at the basilar membrane level. In this report we present data on interactions among SOAEs in ears with multiple SOAEs, including: intermodulation distortion products, mutual suppression, and noncontiguous-linked SOAEs which apparently share energy between two quasi-stable states. These results demonstrate the highly nonlinear and extremely complex nature of the active process, and present a challenge for mathematical modeling of the mechanisms involved.