Variations in the Relative Speeds of Orofacial Structures With Stuttering Severity Stuttering can be characterized in part as a disorder in the coordination of different muscle systems. In light of basic aspects of orofacial physiology and development, the speeds of the lips and tongue relative to the jaw may be an important dimension for evaluating motor coordination among persons who stutter ... Research Article
Research Article  |   December 01, 2000
Variations in the Relative Speeds of Orofacial Structures With Stuttering Severity
 
Author Affiliations & Notes
  • Michael D. McClean
    Walter Reed Army Medical Center Washington, DC
  • Charles M. Runyan
    James Madison University Harrisonburg, VA
  • Corresponding author: e-mail: mdmcclean@hotmail.com
  • Contact Author: Michael D. McClean, PhD, Army Audiology and Speech Center, Walter Reed Army Medical Center, Washington, DC 20307-5001. Email: mdmcclean@hotmail.com
    Contact Author: Michael D. McClean, PhD, Army Audiology and Speech Center, Walter Reed Army Medical Center, Washington, DC 20307-5001. Email: mdmcclean@hotmail.com×
Article Information
Speech, Voice & Prosodic Disorders / Fluency Disorders / Speech / Research Articles
Research Article   |   December 01, 2000
Variations in the Relative Speeds of Orofacial Structures With Stuttering Severity
Journal of Speech, Language, and Hearing Research, December 2000, Vol. 43, 1524-1531. doi:10.1044/jslhr.4306.1524
History: Received March 23, 2000 , Accepted May 8, 2000
 
Journal of Speech, Language, and Hearing Research, December 2000, Vol. 43, 1524-1531. doi:10.1044/jslhr.4306.1524
History: Received March 23, 2000; Accepted May 8, 2000

Stuttering can be characterized in part as a disorder in the coordination of different muscle systems. In light of basic aspects of orofacial physiology and development, the speeds of the lips and tongue relative to the jaw may be an important dimension for evaluating motor coordination among persons who stutter (PWS). To test this idea, an electromagnetic system was used to obtain measures of lip, tongue, and jaw speed in 38 adults (29 PWS and 9 normally fluent speakers, NFS) as they repeated a simple speech utterance at a normal rate. Using categorical ratings of stuttering severity, ratios of tongue speed to jaw speed were significantly greater in PWS rated as severe, compared to NFS and other PWS. Significant increases in lower lip-to-jaw and tongue-to-jaw speed ratios with stuttering severity were also reflected in correlation analyses relating speed ratios to a continuous measure of stuttering severity. These trends in speed ratio were related to increases in lower lip and tongue speed and decreases in jaw speed with stuttering severity. Sources of the speed differences are discussed in relation to underlying muscle activity, motor compensation processes in adults, and the development of orofacial motor control in children who stutter.

Acknowledgments
This research was supported by the Department of Clinical Investigation, Walter Reed Army Medical Center, under Work Units 2546, 2558, and 2585, and was approved by the Center's Human Use Committee. The work also was supported in part by NIH Grant DC03659. All subjects enrolled in the study voluntarily agreed to participate and gave written and informed consent. The opinions or assertions contained herein are the private views of the author and are not to be construed as official or as reflecting the views of the Department of the Army or the Department of Defense. Thanks to Chia-Wen Ko for her advice on statistical analysis and Laura Battiata for her assistance with severity ratings. We also thank Anne Smith, David Ward, and an anonymous reviewer for their helpful suggestions on the manuscript.
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