Effects of tinnitus retraining therapy involving monaural noise generators.

The aim of this study was to assess how tinnitus retraining therapy (TRT) employing monaural noise generators (NGs) affects tinnitus patients. Ninety-five patients with chronic tinnitus were included in this study. All received directive counseling and monaural NGs without any other combination treatment. Effects were evaluated with the Tinnitus Handicap Inventory (THI) 6, 12, and 24 months after the start of treatment. Multiple regression analysis was used to evaluate factors associated with improvement of THI scores. We observed a significant improvement in the average THI scores, which ranged from 59 at baseline to 36 after 6 months and were stable up to 24 months. Severely distressed (SD) patients experienced more benefits from the therapy than moderately distressed (MD) patients. Multiple regression analysis revealed that the presence of transient anxiety symptoms, measured by the state section of the State Trait Anxiety Inventory at the beginning of treatment, were associated the most to a decline in THI scores in SD patients. Pure-tone average at three mid frequencies was a negatively contributing factor. Analysis of MD patients did not provide a good model. In conclusion, TRT employing monaural NGs was an effective intervention especially for SD patients, although plateau of the effects after 6 months may be indicative of limitation of applying NGs monoaurally. Reducing the patients' hearing handicap may reinforce the effects of TRT in SD patients. Additional evaluation and interventions for both SD and MD patients might be needed.