Listener deficits in hypokinetic dysarthria: Which cues are most important in speech segmentation?

Carolyn Ann Wade, Purdue University

Abstract

Listeners use prosodic cues to help them quickly process running speech. In English, listeners effortlessly use strong syllables to help them to find words in the continuous stream of speech produced by neurologically-intact individuals. However, listeners are not always presented with speech under such ideal circumstances. This thesis explores the question of word segmentation of English speech under one of these less ideal conditions; specifically, when the speaker may be impaired in his/her production of strong syllables, as in the case of hypokinetic dysarthria. Further, we attempt to discern which acoustic cue(s) are most degraded in hypokinetic dysarthria and the effect that this degradation has on listeners' segmentation when no additional semantic or pragmatic cues are present. Two individuals with Parkinson's disease, one with a rate disturbance and one with articulatory disruption, along with a typically aging control, were recorded repeating a series of nonsense syllables. Young adult listeners were then presented with recordings from one of these three speakers producing non-words (imprecise consonant articulation, rate disturbance, and control). After familiarization, the listeners were asked to rate the familiarity of the non-words produced by a second typically aging speaker. Results indicated speakers with hypokinetic dysarthria were able to modulate their intensity and duration for stressed and unstressed syllables in a way similar to that of control speakers. In addition, their mean and peak fundamental frequency for both stressed and unstressed syllables were significantly higher than that of the normally aging controls. ANOVA results revealed a marginal main effect of frequency in normal and consonant conditions for word versus nonwords listener ratings.

Degree

M.S.

Advisors

Huber, Purdue University.

Subject Area

Speech therapy|Acoustics

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