Quantitative analysis of vowel production in cerebral palsy children with dysarthria

The present study aimed to identify certain acoustic parameters for speech evaluation in cerebral palsy children with dysarthria.

The subject included 30 native Mandarin-Speaking children with cerebral palsy, who were 5-15 years old, and 13 healthy children in a similar age range. Each subject was recorded while producing a list of 12 Mandarin words, which included three syllables ('ba', 'bi' and 'du'), in all four Mandarin tones. The formants (F1 and F2) of monophthong vowels /a, i, u/ were extracted from each vowel token. Based on F1 and F2, the vowel acoustic indexes VSA, VAI and FCR were calculated and analyzed.

Compared with the control group, the cerebral palsy group had significantly low F1 and F2 in vowel /a/ (P < 0.05), and F2 in vowel /i/ (P < 0.05), while F1 and F2 in vowel /u/ and F1 in vowel /i/ had no significant difference. Between the healthy group and cerebral palsy group, the differences in VSA, VAI and FCR were all statistically significant.

Children with cerebral palsy have reduced vowel space and speech articulation. The significant difference in vowel acoustic indexes (VSA, VAI and FCR) among the two groups revealed that the three indexes were sensitive to the variation of the vowels production in children with cerebral palsy, and that these may be used as an evaluation method of speech intelligibility caused by impaired vowel pronunciation in children with cerebral palsy, and the effect of rehabilitation therapy.