Studies in Parkinson's Disease: I. Perceptual Speech Analyses

The perceptual speech characteristics of a group of 19 subjects with mild-moderate Parkinson's Disease (PD) were compared with those of a normal non-neurologically impaired control group matched for age and sex. Deficits were found in all aspects of speech production, including respiration, phonation, prosody, articulation and resonance. Observed speech deviations were most often mild. The speech deviation which contributed most to the variance in overall intelligibility of speech was imprecision of consonant articulation. Deficits in the phonatory system, including the presence of hoarseness and a strained strangled phonation with intermittent breathiness, were found to be the frequently occurring speech deviations in PD. Disturbed prosodic features were also noted, including a disturbed general stress pattern and a lack of variation in both pitch and loudness levels. The need for careful instrumentally based assessments of the physiological and acoustic features of hypokinetic dysarthria is emphasized.