Temporal and spectral characteristics of speech of children aged 6-7 years with Down syndrome

Down syndrome is a chromosomal disease characterized by peculiarities in the vocal tract structure and muscular hypotonia, which affect the acoustic parameters of the speech signal. The goal of the study is to compare temporal and spectral characteristics of speech of the children with Down syndrome. The study involved 20 children aged 6-7 years: with Down syndrome (DS, n = 10) and typically developing (TD, n = 10). Speech of children was recorded and analyzed according to the procedure developed in the Child Speech Research group at St Petersburg State University. Spectrographic analysis of the speech of children was conducted in the «Cool Edit Pro 2.0» sound editor. Duration and pitch values of words and vowels from the words of children were determined. Formant values were measured, values of formant triangle areas and vowel articulation index (VAI) were calculated. It is shown that duration values of words, stressed and unstressed vowels from the words of children with DS are significantly higher compared with the corresponding characteristics of the speech of TD children. The pitch values of words, stressed and unstressed vowels from the words of children with DS are significantly higher than those of TD peers. Children with DS are characterized by low values of VAI for stressed vowels. The formant triangle area values for unstressed vowels in the words are higher in children with DS. Thus, in the study data on the acoustic characteristics of speech of children with DS were obtained. Differences between children with DS and typically developing children were found.