Comparative Studies of Evoked Otoacoustic Emissions

Nonlinear Stimuli and Linear Stimuli

Abstract

We measured the evoked otoacoustic emissions (EOAEs) to nonlinear stimuli and linear stimuli with an ILO88 device in 22 ears of 13 subjects with normal hearing. The input-output curves and minimal detectable levels were measured.
We used two different methods to evaluate whether EOAEs were present. In method 1, responses were accepted as positive when reproducibility was above 40%. In method 2, responses were accepted as positive when we could visually detect fast and slow components.
There were no significant differences in the total echo power (TEP) or highest peak power (HPP) in response to the two different stimuli above an intensity of 24dBnHL. In a representative case, the inputoutput curves for the responses of both fast and slow components to nonlinear stimuli corresponded with these for the responses to linear stimuli above the minimal detectable levels. The minimal detectable levels of the responses to nonlinear stimuli were significantly higher than those to linear stimuli. The difference between these minimal detectable levels may be related to the linearity of the EOAEs in the range of weak stimuli, which cancelled responses to nonlinear stimuli.