Lip EMG Activity During Vowel Production in Apraxia of Speech Phrase Context and Word Length Effects Research Article
Research Article  |   August 01, 1998
Lip EMG Activity During Vowel Production in Apraxia of Speech
 
Author Affiliations & Notes
  • Monica Strauss Hough
    East Carolina University Greenville, NC
  • Richard J. Klich
    Kent State University Kent, OH
  • Contact author: Monica Strauss Hough, PhD, East Carolina University, Department of Communication Sciences & Disorders, Greenville, NC 27858. E-mail: houghm@mail.ecu.edu
Article Information
Speech, Voice & Prosodic Disorders / Apraxia of Speech & Childhood Apraxia of Speech / Speech, Voice & Prosody / Speech / Research Articles
Research Article   |   August 01, 1998
Lip EMG Activity During Vowel Production in Apraxia of Speech
Journal of Speech, Language, and Hearing Research, August 1998, Vol. 41, 786-801. doi:10.1044/jslhr.4104.786
History: Received March 18, 1997 , Accepted April 21, 1998
 
Journal of Speech, Language, and Hearing Research, August 1998, Vol. 41, 786-801. doi:10.1044/jslhr.4104.786
History: Received March 18, 1997; Accepted April 21, 1998

This investigation examined the timing relationships of EMG activity underlying vowel production in 2 normal individuals and in 2 individuals with marked-tosevere apraxia of speech of approximately two-and-one-half years duration. The timing of lip muscle activity was investigated in monosyllabic words embedded in phrases and in syllable word stems as a function of changes in word length. Specifically, the onset and offset of EMG activity of lip muscles used for production of /u/ in the monosyllables and word stems were examined. The results revealed that the relative amounts of time devoted to onset and offset of EMG activity for lip rounding are disorganized in apraxia of speech. Word length appeared to affect the timing of the onset of muscle activity for both the normal speakers and the speakers with apraxia of speech. Word length also influenced the offset of muscle activity, but its effect was less systematic for the speakers with apraxia of speech. The findings suggest that termination of EMG activity may be at least as disturbed as the initiation of EMG activity in apraxia of speech.

Acknowledgments
The authors would like to thank Malcolm McNeil for his helpful comments on an earlier version of this manuscript. The authors also would like to thank Dr. Joseph Duffy and two anonymous reviewers for their insightful critiques on the manuscript.
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