The control of voice onset time and vowel duration after paraneoplastic cerebellar degeneration: An acoustic study

Abstract

Speech production was examined in a group of six subjects with paraneoplastic cerebellar degeneration, a neurological disorder that produces severe dysarthria. Subjects were recorded repeating CVC and CVCV syllables that included the stop consonant [p b t d k g] and the vowels [i a u]. Vowel durations preceding voiced and voiceless segments and voice onset time (VOT) were measured. The vowel duration measures assessed the preservation of intrinsic duration properties, and the variation of these properties in conditioning phonological contexts. The VOT measure assessed the coordination of two independent articulatory events. Results indicated that the cerebellar subjects normally differentiated among individual vowels, and altered vowel duration as a function of phonological context. In contrast, they tended to reduce VOT for voiceless segments, and, in the case of the most impaired subject, the voiceless segments were always perceived as being voiced. Although the VOT durations were reduced, there was no overlap between voiced and voiceless VOTs for most cerebellar subjects. These results suggest that the temporal coordination of articulatory maneuvers rather than general timing of segmental duration may specifically involve the cerebellum. [Work supported by NS 17778.]