Central Auditory Maturation and Babbling Development in Infants with Cochlear Implants

Objective: To examine the relationship between the maturation of central auditory pathways and the development of canonical (speechlike) babbling in infants with cochlear implants. Design: Comparison of the latencies of the P1 cortical auditory evoked potential and vocalizations produced by subjects before they were fitted with a cochlear implant and at several time points within the first year after implantation. Subjects: Two congenitally deaf children who were implanted with a multichannel cochlear implant at ages 13 and 14 months. Interventions: P1 response latencies were recorded in response to a /ba/ stimulus before implantation and at several time points following implantation. Vocalizations produced by the subjects while interacting with their caregiver were audiorecorded twice before implantation and at monthly sessions following implantation. Results: Subjects showed a rapid decrease in P1 latencies resulting in normal P1 latencies within about 3 months after implantation. Before implantation, the vocalizations were primarily of a precanonical nature. After 3 months' experience with the implants, the proportion of canonical vocalizations increased dramatically relative to the number of precanonical utterances. Conclusions: Results of this study suggest that the development of P1 response latencies and the development of early communicative behaviors may follow a similar developmental trajectory in children implanted early. Although preliminary, these findings indicate that the development of early communicative behaviors following implantation may be positively influenced by the rate of plastic changes in central auditory pathways.