Prespeech vocalizations of a deaf infant: a comparison with normal metaphonological development.

A comparative study of the speech-like vocalizations of a deaf infant and a group of 11 hearing infants was conducted in order to examine the role of auditory experience in the development of the phonological and metaphonological capacity. Results indicated that from 8 to 13 months of age, the deaf subject differed strikingly from hearing infants of comparable age. She produced no repetitive canonical babbling, whereas all the hearing infants produced many canonical syllables. The topography of the deaf infant's vocalizations resembled that of 4-6-month-old (i.e., Expansion stage) hearing infants. Detailed comparisons of the proportion of production of various metaphonologically defined categories by the deaf infant and Expansion stage hearing infants demonstrated many similarities in vocalization, although possible differences were noted. It is concluded that hearing impairment notably affects vocalization development by the end of the first year of life, if not earlier. Spectrographic displays illustrate the categories of infant sounds produced by the deaf and hearing infants.