BackgroundTo date, a large number of acoustic therapies have been applied to treat tinnitus. The effect that produces those auditory stimuli is, however, not well understood yet. Furthermore, the conventional clinical protocol is based on a trial-error procedure, and there is not a formal and adequate treatment follow-up. At present, the only way to evaluate acoustic therapies is by means of subjective methods such as analog visual scale and ad-hoc questionnaires.MethodsThis protocol seeks to establish an objective methodology to treat tinnitus with acoustic therapies based on electroencephalographic (EEG) activity evaluation. On the hypothesis that acoustic therapies should produce perceptual and cognitive changes at a cortical level, it is proposed to examine neural electrical activity of patients suffering from refractory and chronic tinnitus in four different stages: at the beginning of the experiment, at one week of treatment, at five weeks of treatment, and at eight weeks of treatment. Four of the most efficient acoustic therapies found at the moment are considered: retraining, auditory discrimination, enriched acoustic environment, and binaural.DiscussionEEG has become a standard brain imaging tool to quantify and qualify neural oscillations, which are basically spatial, temporal, and spectral patterns associated with particular perceptual, cognitive, motor and emotional processes. Neural oscillations have been traditionally studied on the basis of event-related experiments, where time-locked and phase-locked responses (i.e., event-related potentials) along with time-locked but not necessary phase-locked responses (i.e., event-related (de) synchronization) have been essentially estimated. Both potentials and levels of synchronization related to auditory stimuli are herein proposed to assess the effect of acoustic therapies.Trial registrationRegistration Number: ISRCTN14553550. ISRCTN Registry: BioMed Central. Date of Registration: October 31st, 2017.

Cochrane reviews indicate there is very limited support for all forms of sound therapy and cognitive behavioral therapy has the strongest support. American Academy of Otolaryngology (AAO) recently published some guidelines which recommends Cognitive Behavioral Therapy (CBT) for tinnitus intervention, and only indicates that sound therapy should be considered an "option" for intervention. Nevertheless, acoustic therapy could lead to cause changes in the tinnitus perception and has been appreciated by the affected people for years. In the last decades, the use of sound or sound enrichment has become a central part of many tinnitus management programs used by audiologists, whether the intention was to mask tinnitus, suppress tinnitus, or interrupt the tinnitus generating neural activity. Several acoustic therapies have been developed and implemented in the last 40 years, but how can we determine which one is the most effective? We can determine the effects based on the results reported in many research studies, but in those studies are many factors that differ from one study to another, like in-ear medical devices used to apply acoustic therapy for tinnitus treatment. In this article, we review and analyze the different types of in-ear medical devices used in the most recently acoustic therapies in treatments against tinnitus, allowing us to identify the pros and cons. By our analysis, an optimal medical device could be characterized to enhance the application of acoustic therapies and in consequence the global results of the sound therapies that already exist. In this review, it was considered acoustic therapies, the technology implemented in medical devices and the clinical needs.