Effect of grammar intervention on vocabulary skills in children with a cochlear implant: A single-subject study.

Background: Previous studies have shown that children with cochlear implants have difficulty in grammar acquisition. Vocabulary acquisition and grammar abilities are important during language development. The purpose of this study was to investigate the effect of grammar therapy on the lexical ability of cochlear implanted children. Methods: Five children with cochlear implants and grammatical problems were treated using a grammar task designed for the current study. Before and after the treatment, repeated evaluations were performed using the Mean Length of Utterance (MLU) and Persian Developmental Sentence Scoring (PDSS) indices for grammar and NDW and NTW indices for vocabulary abilities; these show the number of different words and the number of total words respectively. Results: Grammar intervention was successful in cochlear implanted children of the present study. In addition, treatment of grammatical problems increased the lexical ability of all children; NDW and NTW scores increased, which was confirmed by the effect size indices. In the follow-up phase, the cochlear implanted children were able to maintain the increase in NTW and NDW values. Conclusion: Improving grammar skills in cochlear implanted children also increased their lexical ability. Therefore, grammar therapy helps to increase the vocabulary of children too.