Perceptual dialect categorization by an adult cochlear implant user: a case study.

Research on the perception of indexical properties of speech in normal-hearing listeners has revealed that speech perception and spoken word recognition involve not only encoding of the linguistic message, but also processing and storage of talker-specific "indexical" properties of the speech signal, such as age, gender, and dialect. The perceptual processing of talker-specific information in speech has also been shown to affect the speech perception abilities of pediatric and adult cochlear implant users. In the current study, "Mr. S.", a post-lingually deafened adult cochlear implant user with 8 years of implant experience participated in a six-alternative forced-choice perceptual dialect categorization task without training or feedback. Normal-hearing adults can categorize unfamiliar talkers by regional dialect of American English with about 30% accuracy in a six-alternative forced-choice task. While this performance is poor, it is statistically above chance. Like the normal-hearing listeners, "Mr. S."'s performance was also statistically above chance and his scores were within one standard deviation of the mean performance of 30 normal-hearing controls. The present results suggest that "Mr. S." was able to perceive and encode non-linguistic talker-specific information from the speech signal that he received through his implant and use that information in an explicit test of dialect categorization.