Symptomatic differences in decreased alternating motion rates between individuals with spastic and with ataxic dysarthria: an acoustic analysis.

Acoustic analysis was conducted to investigate symptomatic differences in decreased oral alternating motion rates (AMRs) between individuals with spastic and with ataxic dysarthria. The subjects were 6 individuals with spastic dysarthria, 6 with ataxic dysarthria and 6 normal speakers. Monosyllables /pa/ and /ta/ were used to examine alternating motions of the lips and tongue, respectively. In the decreased AMRs of the spastic group, the mean syllable durations were generally longer in the individuals where the mean total syllable durations were longer, and in the decreased AMRs of the ataxic group, the mean gap durations were generally longer in the individuals where the mean total syllable durations were longer. It was suggested that each syllable component could represent a separate function and contribute differently to the decreased AMRs in these dysarthric groups.