Duration-dependent associations of sound therapy on tinnitus in hearing loss: A cross-sectional analysis of treatment duration cohorts

BACKGROUND: This cross-sectional observational study analyzed data from routine clinical practice to compare outcomes across independent treatment duration cohorts (3, 6, and 9 months). METHODS: This retrospective cohort study analyzed data from 85 patients with chronic tinnitus (≥6 months) and hearing loss who received hearing aid-based sound therapy. Patients were grouped by treatment duration (3, 6, or 9 months) based on clinical circumstances. Pure-tone audiometry, tinnitus psychoacoustic matching, and Tinnitus Handicap Inventory (THI) were assessed at baseline and post-treatment. RESULTS: Post-treatment assessments showed significant reductions in THI scores and tinnitus loudness versus baseline (P < 0.05). Repeated-measures ANOVA revealed a significant time × group interaction for THI changes (F = 5.856, P = 0.004), but Bonferroni-corrected pairwise comparisons showed no significant between-group differences. Multivariate ordinal regression identified longer treatment duration as an independent factor associated with better outcomes: the 3-month cohort showed a lower likelihood of improvement compared with the 9-month cohort (OR = 0.141, 95% CI: 0.038-0.513, P = 0.003), while no difference was found between 6- and 9-month cohorts. Hearing loss severity was not associated with efficacy. CONCLUSION: In this observational cohort, hearing aid-based sound therapy was associated with reductions in tinnitus-related handicap and loudness. Longer treatment duration was associated with a higher probability of clinical improvement. Patients showed continued improvement up to 9 months, although causal inference is precluded by the observational design.