Michele L. Steffens

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.

Speech-like vocalizations in infancy: an evaluation of potential risk factors [*]

This work reports longitudinal evaluation of the speech-like vocal development of infants born at risk due to prematurity or low socio-economic status (SES) and infants not subject to such risk. Twenty infants were preterm (10 of low SES) and 33 were full term (16 of low SES), and all were studied from 0;4 through 1;6. The study provides the indication that at-risk infants are not generally delayed in the ability to produce well-formed speech-like sounds as indicated in tape-recorded vocal samples. At the same time, premature infants show a tendency to produce well-formed syllables less consistently than full terms after the point at which parents and laboratory personnel note the onset of the canonical babbling stage (the point after which well-formed syllables are well established in the infant vocal repertoires). Further, even though low SES infants produce well-formed speech-like structures on schedule, they show a reliably lower tendency to vocalize in general, as reflected by fewer utterances per minute in recorded samples.

Development of Speech-like Vocalizations in a Child with Congenital Absence of Cochleas: The Case of Total Deafness.

In order to assess the effect of total deafness on vocalization development, tape recorded utterances of a 3-year-old child who was born without cochleas were examined. In the beginning of the study, the subjects speech consisted almost exclusively of small numbers of sounds characteristic of early infancy. Across the study, the subject participated in extensive vocal stimulation activities. He also initially received intermittent exposure to tactile speech information via a 16-channel vocoder and, subsequently, a 2-channel tactile aid. Following introduction of the 2-channel aid, the subject made rapid improvement in the quality of his vocalizations, which consisted increasingly of speech-like utterances, including well-formed or canonical syllables. These results suggest that, although hearing impairment slows the onset of canonical babbling, even total deafness does not preclude its eventual appearance.

Extreme poverty and the development of precursors to the speech capacity

The study of infant vocal development has suggested that babbling is an important precursor of the speech capacity. In addition, research has shown that the babbling of infants is biologically robust - it develops normally in infants from widely varying environments of language and socio-economic status. Babbling development is so robust that even premature birth does not appear to slow its course in healthy infants.