Do acoustic environment characteristics affect the lexical development of children with CIs? A longitudinal study before and after CI activation

Purpose: The present study investigates the acoustic environment of children with cochlear implants (CIs) and the relationship between exposure to speech, in noise and in quiet, and the children’s lexical production up to one year after CI activation, while controlling for the effect of early individual differences in receptive vocabulary growth. Method: Eighteen children with CIs were observed at three, six, and 12 months after CI activation. Children's spontaneous words production during interaction with their mothers (types and tokens) and their expressive and receptive vocabulary size were considered. The characteristics of the acoustic environments in terms of acoustic scenes (speech in noise or in quiet, quiet, noise, music, and other) and of loudness ranges were assessed using data logging of the children's devices. Results: Data analysis showed that both the number of tokens and the number of types produced one year after CI activation were affected by the children’s exposure to speech in quiet with a loudness range between 40 and 69 dB. Expressive vocabulary size and types were affected by the receptive vocabulary knowledge that the children achieved over the first three months after CI activation. Conclusions: Our data support the role of speech environment and individual differences in early comprehension on lexical production. The importance of exposure to speech with particular characteristics for the lexical development of children with CIs and the implications for clinical practice are discussed.