Auditory feedback experience in phonetic development: Evidence from preschoolers with cochlear implants and their normal-hearing peers

Previous work has found that preschoolers with greater phonological awareness and larger lexicons, who vocalize more throughout the day, exhibit less intra-syllabic coarticulation in controlled speech production tasks. These findings suggest that both linguistic experience and speech motor control are important predictors of spoken phonetic development. Still, it remains unclear how preschoolers' speech practice during vocalizations drives the development of coarticulation because children who vocalize more are likely to have both increased fine motor control and increased auditory feedback experience. Here, the potential effect of auditory feedback is studied by examining a population---children with cochlear implants---naturally differing in auditory experience. Results show that (1) developmentally-appropriate coarticulation improves with increased hearing age, but not chronological age, (2) children with cochlear implants pattern coarticulatorily closer to their younger, hearing age-matched peers than chronological age-matched peers, and (3) the effects of vocalization practice on coarticulation only appear in the children with cochlear implants after several years of hearing experience. Together, these results indicate a strong role of auditory feedback experience upon coarticulation and suggest that parent-child communicative exchanges could stimulate children's own vocal output driving speech development.