Investigating the origin of upper-side-band distortion-product otoacoustic emissions within a micromechanical cochlear model

Upper-side-band distortion-product otoacoustic emissions (DPOAEs) have a higher frequency than either of the stimulus tones (f(1) and f(2)). They are less widely used in clinical practice and their generation is more difficult to understand in comparison to lower side band DPOAEs. We have developed a numerical quasilinear model of the cochlea based on the work of Kanis and de Boer. The model is applied to investigate the source of the 2f(2) - f(1) upper-side-band DPOAE using several complementary approaches, including a novel method of decomposing the predicted cochlear response into forward and backward travelling waves. We conclude that the simulated 2f(2) - f(1) distortion product (DP) consists of contributions from two source mechanisms: A distributed distortion source encompassing both the DP and f(2) characteristic places, and a reflection source at the DP characteristic place