On the large-scale spectral structure of otoacoustic emissions.

Transient evoked and distortion product otoacoustic emission data, showing a characteristic slowly oscillating spectral shape, are presented. Such peculiar behavior had also been observed in earlier studies, and deserves some theoretical explanation. A simple model of the cochlear reflectivity, based on the analogy between the cochlear transmission line equations and the Schrödinger wave equation for the motion of an elementary particle above a one-dimensional potential well, is presented. Wave mechanics predicts indeed reflection from a negative potential well, which is quasiperiodically dependent on the width and depth of the well, i.e., on the quality factor of the cochlear resonance. The model, whose quantitative predictions are dependent on the rather uncertain level and slope of the cochlear tuning curve, proves capable of explaining, at least qualitatively, the observed experimental behavior.