I'm sharing this, as I think it's interesting. Whilst this is an extract from a scientific study about Hyperacusis, it discusses Tinnitus (mentioned 34 times). Im afraid it doesn't have conclusive answers, but further understanding helps me better accept these two apparently interrelated conditions. Hope it might help others out there too.
"Comorbidity between hyperacusis and tinnitus is very high with an estimated 86% of patients with hyperacusis also having tinnitus, 27 to 40% of patients with tinnitus also show symptoms of hyperacusis.
Recent work suggests that tinnitus and hyperacusis are linked to excessive neural activity in a widespread brain network that not only includes the central auditory pathway, but also brain regions involved in arousal, emotion, stress, and motor control."
"Hyperacusis in tinnitus has been associated with younger age, higher tinnitus-related mental and general distress, and higher rates of pain disorders and vertigo. Further, the degree of annoyance due to tinnitus was shown to have no clear relationship with hyperacusis. In our group session, seven of 11 patients suffered from tinnitus and sought help from an otologist."
"Neuroplastic changes in the nervous system caused “central sensitization,” thus reducing the threshold for pain activation and increasing the pain perception with supra-threshold stimulation. This may alter activity at sensory convergence regions in the thalamus and brainstem (such as the locus coeruleus) and give rise to hyperacusis in certain pain syndromes.
Patients with hyperacusis may feel discomfort, be fretful, anxious, nervous, or irritable when hearing certain sounds. These emotional reactions can also be accompanied by related symptoms such as tinnitus, headache, and imbalance. Beyond sound sensitivity, other sensory stimuli can also cause discomfort in some hyperacusis patients. For example, 4/11 participants in our group were bothered by bright light, 5/11 bothered by smell, 1/11 bothered by taste, and 1/11 bothered by touch."
"Hyperacusis is a complex disorder and requires intervention that often involves multiple members of a medical team, including audiologists."
Jai Ke, et al (2020). Complaints of People with Hyperacusis.