Meta-analytic Findings on Early Vocabulary Acquisition Differences between Receptive and Expressive Vocabulary in Toddlers with Cochlear Implants

Objectives: The purpose of this study was to examine the differences in early vocabulary acquisition between toddlers with cochlear implants (CI) and toddlers with normal hearing (NH), and to identify the differences in early vocabulary acquisition according to CI activation period (<12 months vs. ≥12 months) within CI group. In areas in which the difference between groups was significant, we attempted to determine whether the ‘age at implantation’ of the CI group played a role as a moderator. Methods: Nine papers were selected by applying inclusion and exclusion criteria among papers published for about 15 years (2007-2022) and found through searching three databases (Academic Search Complete, PubMed, Google Scholar). Results: There was no significant difference in receptive vocabulary measured by the MacArthur-Bates Communicative Development Inventories (MB-CDI) in CI and NH children, but there was a significant difference in expressive vocabulary. In addition, within the CI group, there was a significant difference in expressive vocabulary according to CI activation period (<12 months vs. ≥12 months). Conclusion: This study confirmed that the expressive vocabulary measured by the MB-CDI may be limited in very young children with CI when compared to their NH peers.