A cochlear model for acoustic emissions

Acoustic emissions, both spontaneous and evoked, were measured in humans and in several animals. There were significant differences in the experimental results. In all animals a strong acoustic distortion product (ADP) was obtained, whereas in 60%–70% of the human subjects ADP was unmeasurable. Those human ears that emitted ADP usually possessed spontaneous emission (SE) and also Kemp's echo. The amplitude of the ADP was stronger when its frequency or the primary‐tones frequency was in the vicinity of SE or near a peak of the Kemp's echo spectrum. In animals, the SE and Kemp's echo were rarely measurable. In order to understand the differences of the emission properties observed in various people and animals, a modification of the cochlear nonlinear transmission‐line model is suggested. On each branch of the transmission line, a noise source was added to simulate cochlear internal noises. To simulate a local cochlear damage, the vertical resistance was modulated. The emitted spectrum predicted by the mode...