Perceptual and acoustic features of dysarthria in multiple system atrophy

Perceptual and acoustic features of speech were studied in a group of 18 individuals (12M, 6F) with multiple system atrophy (MSA). Perceptual analysis included diagnosis of dysarthria type and rating of speech intelligibility, conducted by 2 experienced listeners. Acoustic analysis was performed for 3 tasks: (1) vowel prolongation, (2) alternating motion rate (AMR), and (3) sentence recitation. Acoustic measures included Multi-Dimensional Voice Program (MDVP) analysis (vowel prolongation), syllable and intersyllable pause duration, intensity variation (AMR), and duration of vowels and utterances (sentence recitation). Perceptual analysis indicated that ataxic dysarthria was the most common dysarthria type, either as a single type or in combination with hypokinetic or spastic types. Speech intelligibility ranged from mildly to markedly impaired. Acoustic results revealed abnormal voice characteristics (including high values of frequency and amplitude perturbations), significantly slow and variable AMR performance, and low pairwise variability index, which is consistent with the perceptual impression of scanning speech.