Listener influences on vowel intelligibility

Abstract

Do the acoustic-phonetic parameters that promote highly intelligible speech vary across different listener populations? The current study investigated whether inter-talker differences in American English (AE) vowel intelligibility were maintained across three listener groups: Normal hearing native AE-speaking adults (NH), normal hearing Korean-speaking adults learning AE as a second language (L2), and hearing impaired native AE-speaking adults (HI). These groups heard recordings of 10 AE vowels in /bVd/ context produced in conversational speech style by 12 talkers. The stimuli were mixed with noise and presented for identification in a 10-alternative forced choice task. Vowel intelligibility varied substantially among the talkers. There were significant correlations of talker scores for the NH and HI listeners, but not for NH and L2 listeners. An analysis of acoustic-phonetic vowel features indicated that vowel intelligibility was negatively correlated with vowel space expansion for the HI group, while for the L2 group, intelligibility was positively correlated with vowel duration. These data suggest that although both HI and L2 listeners have difficulty in noisy listening situations, their degraded performance has different underlying causes that lead to substantial differences in the perception of the intelligibility of different talkers. [Work supported by NIH-NIHDCD 02229 and T32-DC00012.]