Distortion-product and click-evoked otoacoustic emissions of normally-hearing adults.

The purpose of this study was to compare distortion-product otoacoustic emissions (DPOEs) and click-evoked otoacoustic emissions (CEOEs) for normally-hearing human adults. The statistical analysis consisted of computing the DPOE and CEOE levels versus frequency corresponding to the 10th, 25th, 50th, 75th, and 90th percentiles among normal adult ears. The mean and standard deviations of the DPOEs and CEOEs were computed. A direct comparison of the DPOE and CEOE data obtained from the same ears showed that, in a 1-4 kHz frequency region, there was a statistically significant correlation between the levels of the two types of otoacoustic emissions. This finding supports the hypothesis that DPOEs and CEOEs arise from some common mechanisms of the cochlea such as active nonlinear biomechanical mechanisms of the outer hair cells.