The objective of this five-year research project is to evaluate an innovative intervention for reduced sound tolerance (i.e., hyperacusis) for hearing impaired persons. The novel intervention is an extension of Tinnitus Retraining Therapy (TRT), which uses directive counseling and low-level sound therapy to habituate the tinnitus percept. TRT also increases loudness discomfort levels (LDLs). This finding has led to a protocol in our Center for treating hyperacusis. A modified form of TRT will be extended to tinnitus-free hearing- impaired patients who are unable to use amplified sound from hearing aids because of their sound intolerance. The validity and efficacy of this intervention will be evaluated in a randomized, double-blind clinical trial that will control for the treatment effects of directive counseling and sound therapy (Aim 1). The clinical trial will have four arms, each enrolling 25 subjects. Arm 1 will receive modified TRT, including directive counseling and sound therapy. Arm 2 will receive directive counseling and placebo sound therapy. Arms 3 and 4, respectively, will receive sound therapy and placebo sound therapy, alone. Changes in LDLs and other performance measures will be monitored for each patient in repeated measurements that will help track progress for each treatment arm. If the intervention is successful, then LDLs are expected to increase over time and, ultimately, reach normal limits for sound tolerance. The temporal course and dynamics of the LDL shifts, changes in related measures of auditory processing, and subjective improvements in sound tolerance will be documented for each patient (Aim 2), and the stability of these functional changes will be monitored over time (Aim 3). Patients treated successfully for hyperacusis will be fitted with hearing aids. The aided performance of each subject will be evaluated and monitored over time to assess the efficacy of amplification and the continued stability of the LDL thresholds and related functional measures (Aim 4). The success rate for each arm of the trial will be established and statistical tests used to help delineate the key components of the intervention, predictive indices of success, the target population, and the processes underlying hyperacusis (Aim 5). In the absence of a proven intervention, the results from this study are potentially of great clinical importance for establishing an effective treatment for reduced sound tolerance among hearing-impaired listeners. The outcomes are also important inasmuch as they provide a test of the generality of TRT theory and the underlying mechanisms.
