Influence of an external rhythm on oral motor control in children and adults

Rhythm has been used in music therapy practice to facilitate speech output in children and adults; however, the underlying mechanism of speech entrainment is not yet understood.

The purpose of this study was to (a) determine the feasibility of using the limb motor response model for testing oral motor entrainment and (b) establish initial data on oral motor entrainment across ages.

Six healthy 7- to 10-year-olds, six 11- to 14-year-olds, and twelve 18-35-year-olds served as participants. The oral motor kinematics of the upper lip, lower lip, and jaw were examined while participants repeated a bilabial syllable, recorded under three conditions: preferred tempo with no stimulus, preferred tempo with a rhythmic auditory stimulus, and 10% faster with a rhythmic auditory stimulus. The Spatiotemporal Index (STI) was computed to determine movement variability in each condition and the Synchronization Error (SE) was calculated to determine deviations from the auditory stimulus.

Successful completion of the protocol by most participants and initial evidence of entrainment supported feasibility. There was a statistically significant difference in the STI for condition and marker placement. There were no significant differences for age.

Oral motor entrainment of isolated syllables may be measured using the motor response model. Although data indicated that children and adults could entrain oral motor movements to the external auditory stimulus, the perceived tempo or the cognitive demands of such tasks may increase oral motor variability.