Prelinguistic vocalizations of hearing-impaired and normally hearing subjects: a comparison of consonantal inventories.

Phonetic transcriptions of 48 babbling samples from 11 normally hearing subjects, aged 4-18 months, and 39 samples from 14 hearing-impaired (HI) subjects, aged 4-39 months, were analyzed to determine the inventory of consonantal phones for each recording session. Group comparisons revealed that inventories of the hearing-impaired subjects were generally smaller than those of the hearing infants and that they evidenced little change in size prior to 20 months. Analysis of place and manner of articulation of supraglottal phones in the inventories showed that, compared with inventories of the normally hearing subjects, inventories of HI subjects with sensori-neural loss tended to have (a) a higher proportion of labial consonants; (b) a higher proportion of prolongable consonants such as nasals, glides and fricatives, and syllabic consonants; (c) a lower proportion of alveolars; and (d) a lower proportion of stops and nonsyllabic affricates. Differences were also observed between the inventories of hearing-impaired subjects with sensori-neural loss and those with conductive loss and between younger and older hearing-impaired subjects. These findings suggest that hearing loss affects the nature of the consonantal repertoire in the prespeech vocalizations of hearing-impaired subjects.