Tinnitus to the inner ear can cause tinnitus, other apparent causes (e.g., temporomandibular joint dysfunction) are difficult to explain. It may be caused by increased neural activity in the auditory brainstem, where the brain processes sounds, causing some auditory nerve cells to become over-excited. The basis of this theory is that many with tinnitus also have hearing loss. Three reviews of 2016 emphasized the large range and possible combinations of pathologies involved in tinnitus, which in turn result in a great variety of symptoms demanding specifically adapted therapies. Even when tinnitus is the primary complaint, audiological evaluation is usually preceded by
Tinnitus retraining therapy called it masking), an integral part of TRT, found no convincing evidence of the efficacy of sound therapy in the treatment of tinnitus. A summary in The Lancet concluded that in the only decent study, TRT was more effective than masking; in another study in which TRT was used as a control methodology, TRT showed a small benefit. A study which compared cognitive behavior therapy (CBT) in combination with the counselling part of TRT versus standard care (ENT, audiologist, maskers, hearing aid) found that the specialized care had a positive effect on quality of life as well as specific tinnitus