Intonation Characteristics of Speech in Children with Intellectual Disabilities

Abstract

In the literature, data on the formation of intonation in Russian-speaking children with mild intellectual disabilities (mental retardation) without genetic syndromes and serious neurological disorders (for example, cerebral palsy) based on the instrumental analysis of children’s speech are absent. The aim of this study was to compare the intonation characteristics of speech in children, aged 5 to 7, with typical development and with mild intellectual disabilities. The participants of the study were 20 children aged 5 to 7: 10 children (5 girls and 5 boys) with typical development (TD group) and 10 children (6 boys and 4 girls) with mild intellectual disabilities (ID group, ICD-10-CM Code F70). Intellectual disabilities were not associated with genetic or severe neurological disorders (non-specific ID). Child speech was taken from the AD-CHILD.RU speech database. Audio and video recordings of speech and behavior of TD group children (in a kindergarten) and ID group children (in an orphanage) were made in the model situation of a “dialogue with an adult”. Two studies were conducted: a perceptual experiment (n=10 listeners – native speakers, researchers in the field of child speech development) and an instrumental spectrographic analysis of child speech. The instrumental analysis of speech was made in the Praat program. The duration of utterances and stressed vowels, pitch values (average, maximum and minimum), pitch range values of utterances, and pitch range values of vowels were analyzed. The perceptual experiment showed that the utterances of ID group children classified as less clear and more emotional than the utterances of TD group children. The task of phrase stress (words highlighted by voice) revealing was more difficult for adults when they were listening to the speech of ID group children vs. TD group children. In ID group children, the values of utterance duration are lower and the values of vowel duration are higher than in TD group children. The average, maximum, and minimum pitch values, the pitch range values of ID group children’s utterances are higher vs. the corresponding parameters of TD group children’s speech. The duration and pitch range values of stressed vowels from ID group children’s words highlighted by intonation are higher than these features of TD group children’s stressed vowels. The pitch contours of stressed vowels from TD group children’s words highlighted by intonation were presented in most cases by the rise of the pitch contour; the pitch contours of stressed vowels from ID group children’s words highlighted by intonation were presented by the fall of the pitch. The dome-shaped vowel pitch contour and U-shaped contour are more frequent in the speech of ID group children vs. TD group children. In the future, the intonation characteristics of speech of children with different diagnoses could be considered as additional diagnostic criteria of developmental disorders.