Acoustic study of speech in Parkinson's disease

Abstract

Parkinson patients' speech was studied to determine which aspects differ from normal aging adult speech and what changes occur in speech when patients are in different neuromotor states—dyskinesia and rigidity. Parkinson patients alternating between dyskinesia and rigidity during dopamine enhancement treatment were recorded in each state while performing speech-imitation tasks presented on a test tape. Fundamental frequency, sound pressure level, duration and rate of syllables, and phrases were measured from spectrograms and power level tracings of the same speech segments in each recording. In contrast with the normal controls, Parkinson patients' speech during both dyskinesia and rigidity was reduced in length of extended phonation, rate of alternating between on-off phonation, and latency of vocal response. For fundamental frequency, speaking rate, syllable duration, and sound pressure level the degree of variation was reduced. The only speech measure differing between rigidity and dyskinesia was a lower sound pressure level during rigidity. The results indicated that Parkinson's disease significantly impairs laryngeal function and that only speech intensity level is affected by dopaminergic induced changes in neuromotor state.