Effect of Dysarthria Type, Speaking Condition, and Listener Age on Speech Intelligibility Purpose The aim of this study was to examine the effect of loud and slow speech cues on younger and older listeners' comprehension of dysarthric speech, specifically, (a) whether one strategy, as opposed to the other, promoted greater intelligibility gains for different speaker groups; (b) whether older and younger listeners' ... Research Article
Research Article  |   February 01, 2017
Effect of Dysarthria Type, Speaking Condition, and Listener Age on Speech Intelligibility
 
Author Affiliations & Notes
  • Megan J. McAuliffe
    Department of Communication Disorders, University of Canterbury, Christchurch, New Zealand
    New Zealand Institute of Language, Brain & Behaviour, University of Canterbury, Christchurch, New Zealand
  • Annalise R. Fletcher
    Department of Communication Disorders, University of Canterbury, Christchurch, New Zealand
    New Zealand Institute of Language, Brain & Behaviour, University of Canterbury, Christchurch, New Zealand
  • Sarah E. Kerr
    Department of Communication Disorders, University of Canterbury, Christchurch, New Zealand
    New Zealand Institute of Language, Brain & Behaviour, University of Canterbury, Christchurch, New Zealand
  • Greg A. O'Beirne
    Department of Communication Disorders, University of Canterbury, Christchurch, New Zealand
    New Zealand Institute of Language, Brain & Behaviour, University of Canterbury, Christchurch, New Zealand
  • Tim Anderson
    New Zealand Brain Research Institute, Christchurch, New Zealand
  • 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 Megan McAuliffe, megan.mcauliffe@canterbury.ac.nz
  • Editor: Krista Wilkinson
    Editor: Krista Wilkinson×
  • Associate Editor: Jack Ryalls
    Associate Editor: Jack Ryalls×
Article Information
Speech, Voice & Prosodic Disorders / Dysarthria / Hearing & Speech Perception / Acoustics / Speech, Voice & Prosody / Research Articles
Research Article   |   February 01, 2017
Effect of Dysarthria Type, Speaking Condition, and Listener Age on Speech Intelligibility
American Journal of Speech-Language Pathology, February 2017, Vol. 26, 113-123. doi:10.1044/2016_AJSLP-15-0182
History: Received November 19, 2015 , Revised May 23, 2016 , Accepted July 11, 2016
 
American Journal of Speech-Language Pathology, February 2017, Vol. 26, 113-123. doi:10.1044/2016_AJSLP-15-0182
History: Received November 19, 2015; Revised May 23, 2016; Accepted July 11, 2016

Purpose The aim of this study was to examine the effect of loud and slow speech cues on younger and older listeners' comprehension of dysarthric speech, specifically, (a) whether one strategy, as opposed to the other, promoted greater intelligibility gains for different speaker groups; (b) whether older and younger listeners' understandings were differentially affected by these strategies; and (c) which acoustic changes best predicted intelligibility gain in individual speakers.

Method Twenty younger and 40 older listeners completed a perceptual task. Six individuals with dysarthria produced phrases across habitual, loud, and slow conditions. The primary dependent variable was proportion of words correct; follow-up acoustic analyses linked perceptual outcomes to changes in acoustic speech features.

Results Regardless of dysarthria type, the loud condition produced significant intelligibility gains. Overall, older listeners' comprehension was reduced relative to younger listeners. Follow-up analysis revealed considerable interspeaker differences in intelligibility outcomes across conditions. Although the most successful speaking mode varied, intelligibility gains were strongly associated with the degree of change participants made to their vowel formants.

Conclusions Perceptual outcomes vary across speaking modes, even when speakers with dysarthria are grouped according to similar perceptual profiles. Further investigation of interspeaker differences is needed to inform individually tailored intervention approaches.

Acknowledgments
We sincerely thank the participants with dysarthria, their families, and the younger and older listeners who participated in this research. Support from the Health Research Council of New Zealand (Emerging Research Project Grant 09/251) is gratefully acknowledged. We also thank the Motor Speech Lab at Arizona State University for helpful suggestions on analysis, Maryam Ghaleh for research assistance, and Dr. Patrick LaShell for initial statistical advice.
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