Further effects of cochlear loss on ICP loudness adaptation, and loudness constancy

Abstract

ICP loudness adaptation depends on an ipsilateral comparison paradigm with a short increasing or decreasing referent value to reveal loudness adaptation. Janson et al. [Br. J. Audiol. 29, 288–297 (1996)] found the intensity-based function for ICP loudness adaptation for those with a high-frequency loss differed significantly from normal listeners. Loss of loudness constancy in normal listeners was consistent, loss in those with a cochlear loss showed a negative progression as intensity increased, as if it were the inverse of recruitment. The purpose of the present study was to compare ICP adaptation to recruitment. ICP adaptation and recruitment were tested in ten high-frequency loss (probably noise induced) and ten age-matched normal hearing individuals. Although the evidence for recruitment was generally found in those with hearing loss, there was no simple relationship to ICP adaptation. Variation among measures of recruitment, implications of abnormal loudness constancy for speech perception, and the possible use of measures of otoacoustic emissions for future studies will be discussed.