2020 Volume 41 Issue 1 Pages 204-208
Otoacoustic emission (OAE) refers to acoustic waves that originate from the cochlea. Since its discovery, various ways have been developed to elicit OAEs; those elicited by short clicks are called transient-evoked (TE) OAEs, and the cubic distortion elicited by two tones are called distortion-product (DP) OAEs. In addition, spontaneous OAEs can be found from some ears without applying any external stimulus. Shera and Guinan proposed a taxonomy of OAEs that consists of three kinds: the linearly reflected emissions, the spontaneous emissions, and the distortion emissions. This article aims to introduce an additional 4th kind of OAEs to the taxonomy. We have shown theoretically that, when a high frequency, large-amplitude suppressor tone is present, it may set up a temporary and reversible impedance mismatch for the traveling waves that pass through its characteristic place. Because of this mismatch, the waves get partially reflected and going backward toward the stapes. The derivation of this ``nonlinear reflection'' mechanism is based on de Boer's quasi-linear, equivalent system framework, and may help explain the controversial tone-burst evoked OAEs experiments obtained in recent years.