Distinct Response Dynamics to Personalized Sound Therapy in Chronic Tinnitus: Sustained Clinical Benefits and a Critical Treatment Window

OBJECTIVES: The objective of this study is to evaluate the 12-mo efficacy and response patterns of personalized sound therapy for chronic tinnitus and to identify the time window most informative for assessing treatment response. DESIGN: In this double-blind, randomized controlled trial, 66 adults with chronic tinnitus were assigned to receive either digital frequency-customized relieving sound (DFCRS), individualized to each participant's tinnitus pitch, or unmodified music (UM) for 12 mo. The primary outcome was change in Tinnitus Handicap Inventory score. Secondary outcomes included anxiety, depression, insomnia, and tinnitus loudness/annoyance. Overlap weighting was used to adjust for baseline imbalances. RESULTS: Both groups improved, but with fundamentally different temporal patterns. UM produced rapid early improvement that plateaued after 6 mo, whereas DFCRS exhibited delayed but progressive and sustained reduction in symptoms throughout the 12 mo. After adjustment, DFCRS was associated with a significantly greater long-term reduction in Tinnitus Handicap Inventory scores compared with UM (adjusted difference: -6.80 points; 95% confidence interval: -13.01 to -0.60; p = 0.036), alongside broader benefits in anxiety and tinnitus-related distress. Notably, attrition analysis revealed that DFCRS responders with higher baseline severity often achieved substantial improvement within 3 to 6 mo, suggesting this period may represent a critical window for evaluating therapeutic response and guiding clinical management. CONCLUSIONS: Personalized sound therapy produces greater relief of chronic tinnitus symptoms and associated conditions and induces a sustained response pattern. The 3- to 6-mo period emerges as a pivotal clinical decision point. These findings support the integration of hypothesis-driven, personalized acoustic neuromodulation into tinnitus management.