Vocal atypicalities of preverbal autistic children.

This study was designed to evaluate the nature of early vocal behaviors in young children with autism. Recent methodological and conceptual advances in the study of infant preverbal vocalizations were used to provide a detailed examination of the vocal behavior of young preverbal children with autism and comparison children with developmental delays. Results revealed that children with autism did not have difficulty with the expression of well-formed syllables (i.e., canonical babbling). However, children with autism did display significant impairments in vocal quality (i.e., atypical phonation). Specifically, autistic children produced a greater proportion of syllables with atypical phonation than did comparison children. Consistent with prior reports, the children with autism also displayed a deficit in joint attention behaviors. Furthermore, the atypicalities in the vocal behavior of children with autism appeared to be independent of individual differences in joint attention skill, suggesting that a multiple process model may be needed to describe early social-communication impairments in children with autism. Data are discussed in terms of their implications for future theoretical and applied research, including efforts to enhance the specificity of early diagnostic procedures.