Acoustic properties of repair sequences in dysarthric conversational speech: An interactional phonetic study

The acoustic properties of intelligibility enhanced modes of speech in disordered populations are of interest to both speech-language pathologists and speech scientists. They inform theories of intelligibility, and point to potential targets for conversationally focused speech therapy. Previous studies looking at the phonetic events associated with the normal to clear speech transformation in disordered speakers have been exclusively experimental in nature. This dissertation used self-repair in naturally occurring spontaneous conversational speech as a window into intelligibility modification. The corpus of data was drawn from conversations between three primary participants, all suffering from a dysarthria secondary to multiple sclerosis, and several members of their social network. Self-repair sequences were identified and extracted and acoustic analyses were conducted in order to compare the trouble source with the repair region. The sequential organization of the surrounding talk was also considered in order to evaluate the communicative impact of the repair attempts. The findings suggest that dysarthric speakers address both the errors of the trouble source while also manipulating some global properties of the speech signal. It was noted that repairs seemed to exploit phonetic parameters that crossed the segmental/prosodic boundary and interaction between short and long domain features was regularly observed. The extent to which the modifications brought about idealized, canonical realizations in the repaired speech was variable and some degree of phonetic disturbance still resided in the repair. Nonetheless, repair attempts were overwhelmingly successful, with only one failed repair attempt found in the corpus. The findings add to the existing literature on interactional phonetics, clear speech, intelligibility, and speech therapy that focuses on understandability in conversation.