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Does Increased F0 Variability Following Treatment Affect Vowel
Perception for Speakers with Parkinson Disease?

Kate Bunton

Fundamental frequency (F0) has been shown to be an important perceptual cue for vowel identification when listeners are presented a distorted speech signal, such as when a speaker is dysarthric (Bunton, 2004). Resynthesis of the F0 contour for sentences produced by speakers with Parkinson disease (PD) results in changes in vowel identification. Correct identification of the vowel target decreased when the F0 contour was flattened. When the F0 contour was “enhanced”, vowel identification increased compared to the speaker’s original productions. Improved F0 variability is a positive outcome of treatment programs designed for speakers with PD; it is of interest to know whether improved F0 variability following treatment produces similar shifts in vowel identification. F0-F1-F2-F3 for target words were measured pre- and post- LSVT treatment for 8 speakers with PD. A perceptual vowel identification task was also completed. Acoustic analysis of post-treatment data revealed increases in F0 variability for all 8 speakers and minimal changes in vowel space. Results of the perceptual task revealed an increase in the number of vowel segments identified as the target vowel compared to pre-treatment productions for 5 of 8 speakers. These findings demonstrate that increases in F0 variability improve listener identification of intended vowel targets.

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