Elderly people often experience difficulties discriminating speakers that are not fully explained by their pure-tone audiograms. This study aimed to disentangle the effects of peripheral hearing loss from other age-related factors on voice discrimination. Discrimination limens (DLs) were measured for voice stimuli independently morphed along two acoustic parameters: fundamental frequency (F0) contour and spectral envelope. Three groups of listeners participated: elderly listeners (EH), young normal-hearing listeners (NH), and young listeners who received stimuli simulating the hearing loss of the EH group (WH). Thresholds for F0 and spectral envelope pattern, obtained as morphing rates, were converted to F0 average and frequency centroid in Hz. Results revealed markedly higher DLs for the EH group compared to both NH and WH groups, while no clear difference was found between the NH and WH groups. Individual DLs showed no clear relationship with pure-tone audiograms at any frequency. These findings suggest that the decline in voice discrimination ability in older adults is not primarily caused by peripheral audibility loss, but rather by supra-threshold processing deficits that are not captured by the pure-tone audiograms.
Mori et al. (Wed,) studied this question.