Coarticulation in dysarthria

Abstract

The dysarthrias are a group of speech disorders resulting from impairment to nervous system structures important for the motor execution of speech. Numerous studies have examined how dysarthria impacts articulatory movements and the resulting changes in vocal tract shape. Few studies of dysarthria, however, consider that articulatory events and their acoustic consequences overlap or are coarticulated in connected speech, although coarticulation has been studied extensively in neurologically normal speakers and figures prominently in normal speech production theories. In so far as coarticulation presumably would have a similar status in a speech production theory of dysarthria, further investigation of coarticulatory patterns in dysarthria appears warranted. The current study will examine intersyllabic, anticipatory vowel-to-vowel coarticulation in normal speakers, and speakers with Multiple Sclerosis, a disease characterized by plaques in the white matter of the CNS. The speech sample consists of 3 repetitions of 16 target words in the phrase ‘‘It’s a____________again.’’ Phrases were produced in normal, loud, and slow speaking conditions. The effect of target word vowels on /ə/ in the word ‘‘a’’ will be inferred from F2 measures. Within conditions, coarticulatory differences will be compared for MS and Control speakers. Coarticulatory differences across speaking conditions also will be examined.