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Pilot Study of Acoustic Therapies for Tinnitus Suppression
Schad ML, Martin JL, Groon K, Morse-Fortier C, Thielman E, Pendergraft P, Gordon S, Henry JA. Pilot Study of Acoustic Therapies for Tinnitus Suppression. Poster session presented at: Ohio Audiology Biennial Conference; 2015 Mar 21; Columbus, OH.
This study tests the potential efficacy of two types of acoustic therapy for tinnitus treatment, based respectively on two prevailing theories for tinnitus generation: (1) The frequency region of the tinnitus is over represented in the auditory system. Frequency regions surrounding a region of hearing loss (i.e., "edge-frequency regions") expand into the regions of hearing loss. This causes edge frequencies to be over represented, causing a release of inhibition and increased spontaneous firing rates of neurons. This theory poses that the tinnitus frequency is located in the edge frequency regions, which is why the notched noise acoustic therapy is used in this study. (2) The tinnitus frequencies are under-represented, which involves increased neural synchrony in the region of hearing loss, similar to phantom limb syndrome. This theory poses that the tinnitus frequency is located in the region of maximum hearing loss, which is why the matched noise acoustic therapy was used in this study.
The Visual Numeric (loudness rating) Scale (VNS) and Tinnitus Functional Index (TFI) will show significant decreases across visits, indicating the acoustic therapy reduces the perceived loudness and functional effects of tinnitus, respectively. VNS and TFI results at the final visit will show that benefits are maintained 2 weeks post acoustic therapy stimulation.
After meeting inclusion criteria during phone screening, participants attended three visits over a 4 week period (0, 2, and 4 weeks). Outcome measures (VNS and TFI) were completed at the beginning of each visit. At the first visit, participants completed psychoacoustic testing via the Tinnitus Evaluation System (TES), a computer automated system that tests frequencies in 1/3 octave intervals between 250 Hz-16 kHz. The TES obtained hearing thresholds and tinnitus loudness matches at each of these frequencies, followed by 30 pitch matches (PM) using the Bayesian method to identify the perceived tinnitus frequency. Participants were randomized into one of three sound therapies; notched noise (1-12 kHz "notched" within a 1 octave range centered around the PM frequency); matched noise (1 octave wide band of noise centered around the PM frequency); and placebo noise (250-700 Hz band of noise). For each participant, the PM values from the TES testing was used to program an iPod Nano via Matlab. During the second visit the listening devices were collected and then redistributed at the third visit.
30 participants have been enrolled, 10 in each group. All participants experience constant bothersome tinnitus, have no significant hearing loss, are not hearing aid users, and are able to complete PM protocol with reliable precision. The last subjects are completing the protocol, and results will be reported.
A strong rationale exists that some form of auditory stimulation can target the cause of tinnitus with the potential to reverse or somehow interrupt tinnitus-related neural changes. This pilot study sets the stage to conduct a systematic study of evidence-based acoustic protocols to examine their ability to suppress tinnitus as well as to reduce the functional effects of tinnitus.