Rate and Loudness Manipulations in Dysarthria Acoustic and Perceptual Findings Research Article
Research Article  |   August 01, 2004
Rate and Loudness Manipulations in Dysarthria
 
Author Affiliations & Notes
  • Kris Tjaden
    University at Buffalo, Buffalo, NY
  • Gregory E. Wilding
    University at Buffalo, Buffalo, NY
  • Corresponding author: e-mail: Tjaden@acsu.buffalo.edu
Article Information
Speech, Voice & Prosodic Disorders / Dysarthria / Hearing & Speech Perception / Acoustics / Speech / Research Articles
Research Article   |   August 01, 2004
Rate and Loudness Manipulations in Dysarthria
Journal of Speech, Language, and Hearing Research, August 2004, Vol. 47, 766-783. doi:10.1044/1092-4388(2004/058)
History: Received July 24, 2003 , Accepted November 21, 2003
 
Journal of Speech, Language, and Hearing Research, August 2004, Vol. 47, 766-783. doi:10.1044/1092-4388(2004/058)
History: Received July 24, 2003; Accepted November 21, 2003
Web of Science® Times Cited: 118

Both rate reduction and increased loudness reportedly are associated with an increase in the size of the articulatory-acoustic working space and improved acoustic distinctiveness for speakers with dysarthria. Improved intelligibility also has been reported. Few studies have directly compared rate and loudness effects for speakers with dysarthria, however, although rate reduction and increasing vocal loudness are common treatment techniques. In the current study, 15 speakers with dysarthria secondary to multiple sclerosis, 12 speakers with dysarthria secondary to Parkinson’s disease (PD), and 15 healthy controls read a passage in habitual, loud, and slow conditions. Rate and loudness variations were elicited using magnitude production. Acoustic measures included articulatory rate, sound pressure level, vowel space area, first moment difference measures, and F2 trajectory characteristics for diphthongs. Ten listeners scaled intelligibility for reading passages produced by the speakers with dysarthria. Relationships between intelligibility estimates and acoustic measures were determined by regression analysis. All speaker groups reduced articulatory rate for the slow condition and increased vocal intensity for the loud condition, relative to the habitual condition. Vowel acoustic distinctiveness, as indexed by vowel space area, was maximized in the slow condition, but stop consonant acoustic distinctiveness, as indexed by first moment difference measures, was maximized in the loud condition. F2 slope measures for diphthongs were not consistently affected by rate or loudness. Scaled intelligibility for speakers with PD also improved in the loud condition relative to both the habitual and slow conditions. Intelligibility estimates for speakers with dysarthria, however, were not strongly related to acoustic measures of supraglottal behavior. Findings are compared with previous studies, and hypotheses for future treatment studies are discussed.

Acknowledgments
Thanks to Jody Caprow, Jessica Kleinhaut, Alexa Kozak, Amy Ludwig, Deanna Rivera, and Ya-ju Yu for assistance with various aspects of the project. This research was supported by National Institute on Deafness and Other Communication Disorders Grant R01 DC04689.
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