Voice Onset Time in Ataxic Dysarthria

In eight patients with a purely ataxic syndrome due to cerebellar atrophy the voice onset time (VOT) of word-initial stop consonants was measured at the acoustic signal. The subjects had been asked to produce sentence utterances including either one of the German minimal pair cognates “Daten” (/datn/, “data”) and “Taten” (/tatn/, “deeds”). In addition, a master tape comprising the target words from patients and controls in randomized order was played to six listeners for perceptual evaluation. Two major findings emerged. First, the cerebellar subjects presented with a reduced categorical distinction of the VOT of voiced and unvoiced stop consonants. Second, the patients' target words with initial unvoiced plosive gave rise to a significantly increased number of misassignments at perceptual evaluation. To some extent comparable VOT disruptions have been noted in apraxia of speech and basal ganglia disorders. Thus, different pathomechanisms might result in similar VOT abnormalities.