A Cochrane review included 6 studies with 553 patients with tinnitus. Studies were varied in design, precluding meta-analysis of the data. Most of trials applied combination therapies, sound therapy with masking/noise generators/sound enrichment was for most of the time combined with an element of counseling. There was no long-term follow up. One study (n=35) reported that users found sound therapy devices subjectively helpful and reported lower levels of tinnitus annoyance with their use but found no significant difference between sound therapy devices, hearing aids or combination instruments. Another study (n=123) found decreased scores on the Tinnitus Handicap Questionnaire at 6 months but this was less than the effect seen for Tinnitus Retraining Therapy and across the board the latter intervention appeared more efficacious. The third study (n=153) showed a general improvement in the Tinnitus Reaction Questionnaire (TRQ) after treatment, although this was due to the combined use of sound therapy and counselling. In the fourth trial (n=45) no method was found to be more efficacious than another. In the fifth trial (n=52) no significant benefit was seen for sound therapy. In the last trial (n=99) none of three treatment forms compared in this study (information, relaxation or sound therapy) were found to be more effective than the others in facilitating tinnitus. No side effects or significant morbidity were reported from the use of sound-creating devices.
Comment: The quality of the evidence is downgraded by study quality (inadequate allocation concealment, short follow-up time), inconsistency (heterogeneity in patients, treatments and outcomes) and imprecise results (limited study size for each comparison).