Comparing variability in speech motor control in dysarthria with perceptual and acoustic assessments

This study examined the relationship of speech variability indices extracted from audio recordings with a range of perceptual and acoustic measures of dysarthric speech. Twenty speakers with hypokinetic dysarthria due to Parkinson’s Disease and ten speakers with ataxic dysarthria due to different underlying neuropathologies engaged in a series of speech and non-speech tasks. Functional Data Analysis was applied to obtain spatial and temporal variability of loudness, fundamental frequency and formant contours extracted from sentence repetitions. Syllable length and maximum vowel intensity were measured in diadochokinetic tasks. Perceptual measures of intelligibility in sentence and passage reading as well as spontaneous speech were obtained by means of a scaling experiment and orthographic transcription. Linear regression models were applied to explore the relationship between spatial and temporal variability and the acoustic and perceptual assessments. The results will be compared separately for the different dysarthria types and discussed with respect to their respective underlying etiologies