Thai Lexical Tones in Children with Autism Spectrum Disorder
One of a core deficit for individuals with Autism spectrum disorder (ASD) is communication impairments. Studies found that some children with ASD have unusual or odd-sounding prosody, i.e. abnormal stress, rate, affect, and intonation.
Lexical tones are a phonetic contrast necessary for conveying meaning in many languages. Thai language is one of the tonal languages which lexical tone dictates meaning. Various speech and language disorders affect the ability to produce lexical tone, thereby seriously impairing individual’s communicative abilities. To the best of our knowledge, there has been no study regarding lexical tones production in children with ASD. This study compares lexical tones production between Thai children with ASD and typically developing (TD) children.
To study acoustic parameters of lexical tones production in Thai children with ASD in comparison with typically developing children.
Sixty-three children aged 6 to 12 years old were participated, 30 children with ASD and 33 TD children matched for age and sex. The children were asked to name each 25 newly developed picture cards of animals, objects and people that covered all 5 Thai lexical tones and their sound were recorded. The PRAAT software was used for the acoustic measurements, i.e. fundamental frequency (f0), fundamental frequency range (f0 range) and tone duration.
The children with ASD produced higher f0 than TD children but there was no significant difference. For f0 range, the children with ASD produced smaller f0 range than TD children in tone 2, 3 and 5 but larger f0 range in tone 1 and 4. There were significant differences among two groups in tone 2, 3 and 4. All TD children produced slightly longer tone duration than that of children with ASD. There were significant differences among two groups in tone 1, 3 and 5
This study revealed the different acoustic characteristics of the five Thai lexical tones produced by the children with ASD and TD children. It is hoped that this study will shed light on future research in perceptual measurements and lead to specific speech therapy.