The Impact of Contrastive Stress on Vowel Acoustics and Intelligibility in Dysarthria Purpose To compare vowel acoustics and intelligibility in words produced with and without contrastive stress by speakers with spastic (mixed-spastic) dysarthria secondary to cerebral palsy (DYSCP) and healthy controls (HCs). Method Fifteen participants (9 men, 6 women; age M = 42 years) with DYSCP and 15 HCs (9 ... Research Article
Research Article  |   January 01, 2017
The Impact of Contrastive Stress on Vowel Acoustics and Intelligibility in Dysarthria
 
Author Affiliations & Notes
  • Kathryn P. Connaghan
    Northeastern University, Boston, MA
  • Rupal Patel
    Northeastern University, Boston, MA
  • Disclosure: The authors have declared that no competing interests existed at the time of publication.
    Disclosure: The authors have declared that no competing interests existed at the time of publication. ×
  • Correspondence to Kathryn P. Connaghan: k.connaghan@neu.edu
  • Editor: Julie Liss
    Editor: Julie Liss×
  • Associate Editor: Julie Liss
    Associate Editor: Julie Liss×
Article Information
Speech, Voice & Prosodic Disorders / Dysarthria / Speech, Voice & Prosody / Speech / Research Articles
Research Article   |   January 01, 2017
The Impact of Contrastive Stress on Vowel Acoustics and Intelligibility in Dysarthria
Journal of Speech, Language, and Hearing Research, January 2017, Vol. 60, 38-50. doi:10.1044/2016_JSLHR-S-15-0291
History: Received August 20, 2015 , Revised April 29, 2016 , Accepted July 9, 2016
 
Journal of Speech, Language, and Hearing Research, January 2017, Vol. 60, 38-50. doi:10.1044/2016_JSLHR-S-15-0291
History: Received August 20, 2015; Revised April 29, 2016; Accepted July 9, 2016

Purpose To compare vowel acoustics and intelligibility in words produced with and without contrastive stress by speakers with spastic (mixed-spastic) dysarthria secondary to cerebral palsy (DYSCP) and healthy controls (HCs).

Method Fifteen participants (9 men, 6 women; age M = 42 years) with DYSCP and 15 HCs (9 men, 6 women; age M = 36 years) produced sentences containing target words with and without contrastive stress. Forty-five healthy listeners (age M = 25 years) completed a vowel identification task of DYSCP productions. Vowel acoustics were compared across stress conditions and groups using 1st (F1) and 2nd (F2) formant measures. Perceptual intelligibility was compared across stress conditions and dysarthria severity.

Results F1 and F2 significantly increased in stressed words for both groups, although the degree of change differed. Mean Euclidian distance between vowels also increased with stress. The relative probability of vowels falling within the target F1 × F2 space was greater for HCs but did not differ with stress. Stress production resulted in greater listener vowel identification accuracy for speakers with mild dysarthria.

Conclusions Contrastive stress affected vowel formants for both groups. Perceptual results suggest that some speakers with dysarthria may benefit from a contrastive stress strategy to improve vowel intelligibility.

Acknowledgments
This work was supported by the Ethel & Jack Hausman Clinical Research Scholars Award of the Cerebral Palsy International Research Foundation and a New Century Scholars grant from the American Speech–Language–Hearing Foundation. Support for the collection of the speech samples was provided by National Institutes of Health Grant DC-06118. The authors are grateful to Michelle Hoblit and Chelsea Wertheim for their assistance with data collection and analysis. Finally, this work could not have been completed without the generous contribution of the participants' time.
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