Effect of Rate Reduction and Increased Loudness on Acoustic Measures of Anticipatory Coarticulation in Multiple Sclerosis and Parkinson's Disease The present study compared patterns of anticipatory coarticulation for utterances produced in habitual, loud, and slow conditions by 17 individuals with multiple sclerosis (MS), 12 individuals with Parkinson's disease (PD), and 15 healthy controls. Coarticulation was inferred from vowel F2 frequencies and consonant first-moment coefficients. Rate-related changes in coarticulation differed ... Research Article
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Research Article  |   April 01, 2005
Effect of Rate Reduction and Increased Loudness on Acoustic Measures of Anticipatory Coarticulation in Multiple Sclerosis and Parkinson's Disease
 
Author Affiliations & Notes
  • Kris Tjaden
    University at Buffalo, Buffalo, NY
  • Gregory E. Wilding
    University at Buffalo, Buffalo, NY
  • Contact author: Kris Tjaden, Department of Communicative Disorders and Sciences, University at Buffalo, 122 Cary Hall, 3435 Main Street, Buffalo, NY 14214-3023. E-mail: tjaden@acsu.buffalo.edu
Article Information
Hearing & Speech Perception / Acoustics / Speech, Voice & Prosody / Speech / Research Articles
Research Article   |   April 01, 2005
Effect of Rate Reduction and Increased Loudness on Acoustic Measures of Anticipatory Coarticulation in Multiple Sclerosis and Parkinson's Disease
Journal of Speech, Language, and Hearing Research, April 2005, Vol. 48, 261-277. doi:10.1044/1092-4388(2005/018)
History: Received January 19, 2004 , Accepted July 7, 2004
 
Journal of Speech, Language, and Hearing Research, April 2005, Vol. 48, 261-277. doi:10.1044/1092-4388(2005/018)
History: Received January 19, 2004; Accepted July 7, 2004
Web of Science® Times Cited: 12

The present study compared patterns of anticipatory coarticulation for utterances produced in habitual, loud, and slow conditions by 17 individuals with multiple sclerosis (MS), 12 individuals with Parkinson's disease (PD), and 15 healthy controls. Coarticulation was inferred from vowel F2 frequencies and consonant first-moment coefficients. Rate-related changes in coarticulation differed depending on the particular phonetic events in an utterance. In some instances, the slow condition was associated with stronger anticipatory effects, but in other instances the slow condition was associated with weaker anticipatory effects, relative to other speaking conditions. In contrast, coarticulatory patterns for the loud and habitual conditions typically did not differ. Coarticulatory patterns also tended to be similar among speaker groups within each condition. Finally, when acoustic measures of coarticulation differed among speaking conditions, the direction and magnitude of the effect generally were similar for healthy controls, speakers with MS, and speakers with PD. These results are consistent with studies suggesting mostly preserved patterns of coarticulation for speakers with mild to moderate dysarthria, as well as research indicating only subtle coordination deficits for individuals with dysarthria. The finding that increased loudness had a negligible effect on coarticulation also appears to be at odds with the suggestion that increased loudness stimulates orofacial coordination for speakers with dysarthria, although studies including speakers exhibiting coordination impairments at habitual speaking rates would provide a stronger test of this suggestion. Lastly, the fact that speaking condition similarly affected acoustic measures of anticipatory coarticulation for all speaker groups suggests the feasibility of applying theories and models of speech production for neurologically normal talkers to the study of dysarthria.

Acknowledgments
This research was supported by National Institute on Deafness and Other Communication Disorders Grant R01 DC04689. Thanks to Jody Caprow, Jessica Kleinhaut, Alexa Kozak, Amy DiPasquale, Deanna Rivera, and Ya-ju Yu for assistance with various aspects of the project. Portions of this study were presented at the 2003 Convention of the Acoustical Society of America and the 2004 Conference on Motor Speech.
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