Evoked otoacoustic emissions, suppression and comparison to loudness constancy, at speech frequencies

Abstract

Spontaneous otoacoustic emissions (SOAE) reflect spontaneous activity of the outer hair cells of the cochlea. Suppression of transient evoked otoacoustic emissions (TEOAE) bears operational similarity to loudness adaptation determined by the ipsilateral comparison paradigm (ICP). The present study gathered these measures from 41 normal hearing adults (5 male, 36 female, 20–45 years old). There was no significant relationship between spontaneous SOAE, but there was a significant relationship (r =−0.36, p<0.05) between ICP loudness adaptation and suppression of TEOAEs. The relationship between these two active measures has implications for failure of adaptation or the apparent loudness constancy in the speech range revealed by simple adaptation measures. It has been previously noted that the ICP technique yields adaptation in the speech frequencies between 40 and 80 dB, where the simple adaptation apparently does not [Weiler, Sandman, and Dou, program abstract 4pPPa10, J. Acoust. Soc. Am. 101, 3177 (1997)]. Implications will be discussed in terms of the results uncovered in this study.