Acoustic vowel space and speech rate in Mandarin-speaking children with cerebral palsy

This study examines the variability in speech production in 4 Mandarin-speaking children: two with cerebral palsy (CP) and two typically developing (TD) from 4 to 5 years of age. Recordings collected from the picture-naming task and spontaneous interaction was analyzed. Acoustic vowel space and speech rate were investigated. Study findings indicated: 1) Due to defect in speech motor control, children with CP have a smaller overall vowel space; 2) In CP group, there are more variability of formant values of individual vowels and the vowel space of individual vowels thus overlap more; 3) There is a trend of decrease of vowel formant values in both TD and CP; 4) Children with CP tend to spend more time in speech production because of their impaired speech-motor control, in terms of syllable per minute and intelligible syllable per minute; and 5) Slower speech rate seems to increase speech intelligibility in CP. However, this needs to be verified in further studies. Extended longitudinal observation can provide more complete profile of individual differences in the development of vowels and speech rate to verify these preliminary findings. The variability features in the production of children with CP provide important references in speech therapy.