The influence of hearing impairment on preverbal emotional vocalizations of infants.

The aim of the study was to compare the vocalizations of normally hearing and profoundly hearing-impaired infants in the first year of life. After the first recording all hearing-impaired infants were provided with hearing aids. We focused on three issues: (1) Are there different types of preverbal vocalizations in the vocal repertoire of normally hearing and hearing-impaired infants? (2) Do the vocal types emerge at similar age? (3) Does hearing impairment influence the acoustic structure of the preverbal vocalization types common to normally hearing and hearing-impaired infants? The study shows that both normally hearing and hearing-impaired infants have the same vocal repertoire. Except for babbling, there were no differences in the time of emergence of preverbal utterances. Structural differences could only be found in 'cries'. In general, it seems that normal auditory input is not essential for the production of single preverbal utterances.