Jeffrey D. Travis
R. Joe Thornhill
Appl. Res. Labs., Univ. of Texas at Austin, P.O. Box 8029, Austin, TX 78713-8029
A novel approach to finding information in transient-evoked otoacoustic emissions (TEOAEs) was used: the discrete wavelet transform. It is argued that wavelet transforms are more appropriate than fast Fourier transforms (FFTs) for signal decomposition because of the transient, nonstationary nature of TEOAEs. Several wavelets were used to obtain time--frequency maps of TEOAEs collected in past experiments. The latency of several frequency bands can be clearly determined for any given subject with this map. Another set of data collected from an experiment in which subjects were administered quinine sulfate was also studied. Quinine sulfate suppresses TEOAEs and induces some hearing loss [D. McFadden and E. G. Pasanen, J. Acoust. Soc. Am. 95, 3460--3474 (1994)]. Wavelet analysis on this data revealed any temporal shifts of frequency bands during the effect of the drug, and correlated the TEOAE waveform with the amount of temporary hearing loss at each frequency band.