The Effects of Changes in Vocal Loudness on Measures of Speech Physiology in Children with Cerebral Palsy and Typically Developing Children

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  • Cerebral palsy (CP) is a neurodevelopmental disorder that can involve the speech motor control in a large percentage of those having the disorder. This study aims to describe respiratory and laryngeal subsystems involved in speech motor control in children with CP by investigating one of the techniques that targets healthy vocal loudness levels.

    Eight English-speaking children, four with CP and four without, were prompted to repeat sentences and produce maximum phonation duration. Children were cued to adjust their vocal loudness levels to perceived conversational, half conversational, twice conversational, and four times conversational loudness. Participants repeated a sentence five times under all perceived loudness conditions. Participants also produced three maximum phonation duration under conversational loudness and perceived twice conversational loudness conditions. The speech data were analyzed for intercostal-oblique intermuscular coherence, fundamental frequency (F0) mean, vowel duration, and vowel space.

    The results indicate that intercostal-oblique intermuscular coherence visually changed across tasks in both participant groups, especially in the older participants. F0 average and vowel duration increased with increased perceived vocal loudness in the control group, but only F0 average changed with loudness in the group with CP. Vowel space became more peripheral in both groups with increased perceived loudness. Based on these results, young children may make loudness adjustments by increasing chest wall muscular activity and neuromuscular drive to the chest wall. All children seem to make different degrees of laryngeal adjustments to increase loudness levels during speech, as evidenced by significant acoustic changes. This paper provides a descriptive analysis of intermuscular coherence and speech acoustics in children, which serves as a baseline for speech therapies that can lead to biomechanical and neuromuscular efficiency in the speech of children with CP.

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    Research Material
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    Attribution-NonCommercial 4.0 International