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Interactions in the labial musculature during speech
J W Folkins1, R N Linville, J D Garrett
1University of Iowa.
Journal of Speech and Hearing Research
|June 1, 1988
Summary
Speech articulation involves coordinated upper and lower lip muscle activity. This study found positive correlations between lip muscle bursts during speech, indicating flexible interactions rather than complementary muscle variations.
Area of Science:
- Speech Science
- Biomechanics
- Neurophysiology
Background:
- Understanding labial muscle coordination is crucial for speech production.
- Previous research suggested complementary muscle activity patterns during speech.
Purpose of the Study:
- To investigate the electromyographic (EMG) interactions between upper and lower lip muscles during speech.
- To determine if lip muscle activity exhibits symmetric or asymmetric interactions.
Main Methods:
- Four pairs of electrodes were used to record EMG activity from the labial musculature of four young adults.
- Muscle activity bursts related to bilabial closure were manipulated.
- Lower lip closing movements were measured and correlated with muscle activity.
Main Results:
- Manipulation of muscle activity in one lip region typically resulted in positively correlated changes in other lip regions.
- Similar positive correlations were observed regardless of whether upper or lower lip activity was manipulated, suggesting no asymmetry.
- Lower lip movement correlated with modulated muscle activity, indicating adjustments in lip opening based on closing forces.
Conclusions:
- Labial speech production demonstrates a flexible system with positively correlated muscle activity across different lip regions.
- Findings contrast with theories proposing complementary (negatively correlated) muscle variations.
- The system adapts to accommodate varying motor commands and forces during speech.