Acoustic analysis of speech timing in Huntington's disease

Duration measurements at the acoustic speech signal of sentence utterances including syllable lengths, vowel durations, and voice-onset-time (VOT) were performed in 13 subjects with Huntington's disease (HD) and in 12 control speakers. First, all 13 HD subjects presented with increased variability of utterance duration and/or VOT. Second, a subgroup had reduced speech tempo concomitant with overproportional lengthening of short vowels. Presumably, these deviations result from slowed movement execution (bradykinesia) and delayed between-movement transitions. Third, durational parameters of phonetic timing, e.g. stress contrast, were largely unimpaired. In a further patient (HD14) severely reduced articulatory accuracy did not allow acoustic measurements. He presented with truncated, barely intelligible, diphthongized sentence utterances. A slight tendency for these deviations could be noted in two of the HD subjects who underwent acoustic analysis. Since all three subjects had a rather long disease duration, this constellation might represent an advanced stage of HD dysarthria into which the other syndromes ultimately will develop.