Role of infant vocal development in candidacy for and efficacy of cochlear implantation.

Previous research has documented the importance of audition in the development of typical infant vocalization. Of particular interest is the development of canonical babbling, which is related to mastery of the timing elements of speech. Children with severe to profound hearing loss who use hearing aids have demonstrated both delayed and deviant canonical babbling. The vocal development of 12 children has been followed as they have been considered for cochlear implantation. Nine of these children have undergone implantation, and 5 of these children have been followed for more than 1 year after implantation. On average, canonical babbling emerged at 6.5 months after implantation. The time frame in which some children developed words was accelerated in terms of length of auditory experience as compared with normal-hearing peers. Mature oral-motor development is likely the primary contributing factor in this time course. One child who received a cochlear implant began to babble with hearing aids. It is not known whether normal canonical babbling is sufficient evidence on which to base candidacy decisions; however, our data suggest that children who produce canonical babbling maintain and build upon those skills after implantation.