Moving time window analysis of transiently evoked otoacoustic emissions

We have developed a technique for off-line analysis of transient otoacoustic emissions. The correlation of two curves was calculated in a moving time-window of 1 ms time sections. By this method it is possible to recognize high-correlation parts, time sections with low correlation, and thus the duration of the emission can be determined. The mean absolute duration of transiently evoked otoacoustic emissions in 36 normal ears was 15.1 +/- 0.69 ms (mean +/- SE). The duration was significantly shorter (9.34 +/- 0.43) in 75 ears with different grades of sensorineural hearing loss. The breakdown of this group into sub-groups according to the width of the high frequency band with elevated threshold showed a correlation between the severity of the hearing loss and the absolute duration.