Speech and pause characteristics following speech rate reduction in hypokinetic dysarthria

The effect of speech rate reduction on speech and pause characteristics during a reading task was examined for speakers with Parkinson's disease (PD) and a group of control speakers. Duration of utterances and characteristics of pausing (duration, interpause phrase length, and location) were determined. At habitual reading rate, subjects with PD had shorter speech duration and greater time per pause than control subjects. At reduced reading rates, subjects with PD increased speech duration so that it was equivalent to the control speakers at habitual rate. Both groups had the majority of their pause occurring at appropriate syntactic boundaries. Subjects with PD had a greater proportion of pauses occurring at syntactically inappropriate locations than did the controls. When speech rates were reduced, both groups showed a decrease in pauses located at appropriate syntactic boundaries. The implication of these findings on speech intelligibility is discussed.