On the topic of sound therapy for tinnitus and hyperacusis:
1. The study "Effect of Tinnitus Retraining Therapy vs Standard of Care on Tinnitus-Related Quality of Life" in the year 2019 compared the outcomes for three different patient groups (about 50 patients in each group for a total of 150): 1. Tinnitus Retraining Therapy with sound generators (TRT) with tinnitus counseling; 2. placebo TRT with tinnitus counseling; 3. standard of care (just counseling it seems). There was no clinically meaningful difference in extent of reduction in tinnitus distress or other important end points among patients in the 3 different groups. Tinnitus Retraining Therapy with conventional sound generators thus has been found to be no better than Tinnitus Retraining Therapy with placebo generators or standard of care.
2. The study "A Phenotypic Comparison of Loudness and Pain Hyperacusis: Symptoms, Comorbidity, and Associated Features in a Multinational Patient Registry" in the year 2021 noted the following on the use of sound therapy for hyperacusis:
"Of our sample, over 50% of each group [note: about 90 for pain hyperacusis, about 50 for loudness hyperacusis] had attempted to treat their hyperacusis with sound therapy, including both self-directed protocols and those prescribed by professionals (pain: 59.9%, loudness: 53.8%; OR = 1.273 [0.763, 2.173], BF 10 = 0.248, BF ROPE = 0.141). The most common form of sound therapy was self-administered pink noise (n= 85), followed by self-administered white noise (n= 84), structured interventions that included counseling (n= 58), tinnitus retraining therapy (n=55),"Other"(n=48), hearing-aid sound generators (n= 26), and the Neuromonics protocol (n= 3). Participants reported engaging in sound therapy for a median of 1–2 years, with the loudness hyperacusis group reporting a moderately longer duration of sound therapy compared to the pain hyperacusis group (d=−0.525 [−0.908, −0.137], BF 10 =8.42,BF ROPE =7.55). Notably, the loudness group also reported more perceived benefit from sound therapy than the pain group (d=−0.425 [−0.806, −0.047], BF 10 =3.12,BF ROPE = 2.84). Individuals in the loudness group were substantially more likely to report that sound therapy resulted in "significant improvement"or "hyperacusis [being] almost eliminated"(pain: 4.4%, loudness: 22.4%; OR = 0.176 [0.054, 0.557]). However, the proportions of patients reporting (a) no change in symptoms with sound therapy (pain: 38.5%, loudness: 32.7%; OR = 1.274 [0.618, 2.605], BF ROPE = 0.162) or (b) worsening tinnitus/hyperacusis (pain: 27.5%, loudness: 18.4%; OR = 1.616 [0.702, 3.801], BF ROPE = 0.313) did not differ meaningfully between the two groups."
To summarize the results:
Treatment duration: median of 1-2 years (not placebo controlled, so not doing anything could have resulted in the same outcome).
For loudness hyperacusis:
Patients: around 50
Significant improvement: 22,4%
Minor improvement (hinted at on page 14 of the study, missing difference for getting 100% of patients): 26,5%
No change: 32,7%
Worsening (any amount): 18,4%
For pain hyperacusis/noxacusis:
Patients: around 90
Significant improvement: 4,4%
Minor improvement (mentioned on page 14 of the study, missing difference for getting 100% of patients): 29,6%
No change: 38,5%
Worsening (any amount): 27,5%