Coordination of Lip Muscle Activity by 2-Year-Old Children During Speech and Nonspeech Tasks This investigation was designed to quantify the coordinative organization of lip muscle activity of 2-year-old children during speech and nonspeech behaviors. Electromyographic (EMG) recordings of right upper and lower lip activity of seven 2-year-old children were obtained during productions of chewing, syllable repetition, lip protrusion, and speech (repeated two-word utterances) ... Research Article
Research Article  |   December 01, 1997
Coordination of Lip Muscle Activity by 2-Year-Old Children During Speech and Nonspeech Tasks
 
Author Affiliations & Notes
  • Jacki L. Ruark, PhD
    Department of Audiology and Speech Pathology, University of Tennessee, 444 South Stadium Hall, Knoxville, TN 37996
  • Christopher A. Moore
    University of Washington Seattle
  • Corresponding author: e-mail: jruark@utk.edu.
Article Information
Swallowing, Dysphagia & Feeding Disorders / Speech, Voice & Prosody / Speech / Research Articles
Research Article   |   December 01, 1997
Coordination of Lip Muscle Activity by 2-Year-Old Children During Speech and Nonspeech Tasks
Journal of Speech, Language, and Hearing Research, December 1997, Vol. 40, 1373-1385. doi:10.1044/jslhr.4006.1373
History: Received September 18, 1996 , Accepted June 17, 1997
 
Journal of Speech, Language, and Hearing Research, December 1997, Vol. 40, 1373-1385. doi:10.1044/jslhr.4006.1373
History: Received September 18, 1996; Accepted June 17, 1997

This investigation was designed to quantify the coordinative organization of lip muscle activity of 2-year-old children during speech and nonspeech behaviors. Electromyographic (EMG) recordings of right upper and lower lip activity of seven 2-year-old children were obtained during productions of chewing, syllable repetition, lip protrusion, and speech (repeated two-word utterances) tasks. Task comparisons revealed that the coordinative organization of upper and lower lip activity is task specific; different coordinative strategies are employed for different tasks. Lip protrusion and syllable repetition tasks yielded strong coupling of upper and lower lip activity. Lip rounding (sentences containing the lip-rounding vowel /u/) and "nonlabial" speech tasks (sentences free of bilabials and lip-rounding vowels) resulted in low coupling of upper and lower lip activity. Moderate levels of coupling of upper and lower lip activity were evident for chewing and bilabial speech tasks (sentences loaded with bilabial plosion). This finding, that the coordinative elements of the perioral system of 2-year-olds are task specific, extends the results of previous studies of adults and children, where task-specific coordinative strategies were employed by the mandibular and perioral systems Moore, 1993; Moore & Ruark, 1996; Moore, Smith, & Ringel, 1988; Wohlert & Goffman, 1994). The task-dependent coordination of the perioral system of 2-year-olds supports the notion that developing speech and earlier developing oromotor behaviors (i.e., sucking, chewing) are mediated by different control mechanisms.

Acknowledgments
Both authors are formerly of the Department of Communication Sciences and Disorders, University of Pittsburgh, Pittsburgh, Pennsylvania, which also provided support for this investigation. This work was also supported by research grant number 7R29DC00822 from the National Institute on Deafness and Other Communication Disorders, National Institutes of Health.
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