Title: Effectiveness of domain-based intervention for language development in Japanese hearing-impaired children: a multicenter study Abbreviated form: Domain-based language intervention for hearing-impaired children

Objective: Decreasing language delay in hearing-impaired children is a key issue in the maintenance of their quality of life. Language training has been presented mainly by experiencebased training; effective intervention programs are crucially important for their future. The aim of this study was to confirm the efficacy of 6-month domain-based language training of schoolaged, severe-to–profound hearing-impaired children. Methods: We conducted a controlled before-after study involving 728 severe-to–profound prelingual hearing-impaired children, including an intervention group (n=60), control group (n=30), and baseline study group (n=638). Language scores of the participants and questionnaires to the caregivers/therapists were compared before-after the intervention. Average monthly increase in each language score of the control and baseline study group were compared with those of the intervention group. Results: Language scores and the results of the questionnaire of the intervention group showed a significant improvement (p<0.05). The average monthly language growth of the intervention group was twice that of the control group and three to four times that of the baseline study group (p<0.05). The effect size was largest in communication (1.914), followed by syntax (0.931). Conclusion: Domain-based language training improved the language development and daily communication of hearing-impaired children without any adverse effects.