Time-frequency analysis of neonatal click-evoked otoacoustic emissions

Click-evoked otoacoustic emissions (CEOAEs) of full-term babies were considered. By means of the wavelet transform, each CEOAE was decomposed into frequency bands. The rms amplitude and test-retest correlation were computed from these bands. The results indicated that both the amplitude and correlation were not invariant with time but reached a maximum in specific time windows, depending on the frequency of the component. For all components, the correlation was greatly decreased for latencies >12.5 ms. As a result, comparison between the performance of the default ILO 88 window (2.5-20 ms) and the 2.5-12.5 ms window showed that for all frequencies in the 1.5-6 kHz range there was a statistically significant improvement in the correlation.