Approaches to Auditory Rehabilitation for Mild Traumatic Brain Injury

Many soldiers returning from their recent service in Operation Iraqi Freedom/Operation Enduring Freedom (OIF/OEF) were exposed to blasts during combat. About 60% of blast-injured soldiers are diagnosed with traumatic brain injury (TBI), with approximately 18% having a mild TBI (mTBI). mTBI is associated with many symptoms, including memory problems, headaches, difficulty concentrating, increased anxiety, and, especially relevant here, reports of difficulty understanding speech in noisy environments and/or when people speak rapidly. While problems understanding rapid speech or speech in noise are associated with hearing loss, many of the OIF/OEF veterans with these complaints have clinically normal hearing. Although there is no physical damage to their ears, these veterans' hearing problems have a negative impact on their quality-of-life and functioning. Thus it is incumbent upon the VA to examine intervention approaches for veterans with normal/near-normal auditory sensitivity and significant complaints of difficulty hearing. Currently, there is no standard-of-care for these veterans other than providing information about hearing, hearing conservation, and the use of communication strategies. Two forms of rehabilitation likely to be more effective than such an informational-counseling approach are: (1) the use of personal miniaturized Frequency modulation (FM) systems, and (2) the provision of auditory training with Posit Science Brain Fitness Program (BFP). Personal FM systems increase the loudness of the speech signal relative to that of the unwanted noise, while the BFP training improves the ability to listen by taking advantage of the brain's ability to change (i.e., neural plasticity). In this study veterans will randomly be selected to receive one of four treatments: (1) FM use alone, (2) BFP training alone, (3) FM+BFP training combined, and (4) informational-counseling. The effectiveness of the interventions will be compared using self-report of hearing functioning on standard questionnaires. Results will contribute to the development of evidence-based intervention approaches for blast-exposed veterans with reported functional hearing difficulties and normal/near-normal auditory sensitivity.

The long-term goal of this study is to develop evidence-based auditory rehabilitation for veterans who have normal/near-normal peripheral auditory function and significant complaints of difficulty hearing. Many are veterans of the OIF/OEF conflicts who have been exposed to blast - the most common wounding etiology in these conflicts. Approximately 18% of blast-injured veterans are diagnosed with mild traumatic brain injury (mTBI). mTBI can result in post-concussive symptoms such as memory problems, difficulty concentrating, increased anxiety, and functional hearing difficulties in the presence of clinically-normal hearing sensitivity.

Currently there is no standard-of-care auditory rehabilitation for veterans with normal/near-normal auditory sensitivity and complaints of difficulty hearing. At a minimum, the VA recommends provision of information about the auditory system, hearing conservation and use of communication strategies. Two interventions likely to be more efficacious are: (1) use of personal FM (frequency modulation) systems, and/or (2) auditory training. FM systems are effective for managing auditory problems in children with normal/near normal peripheral hearing. FM systems substantially improve the signal-to-noise ratio of speech in noisy and reverberant environments, theoretically making more resources available for higher level processing. Auditory training takes advantage of neural plasticity. The Posit Science Brain Fitness Program (BFP) is an auditory training program for adults that can improve temporal processing and working memory of older adults. Combining use of FM systems with auditory training has been shown to improve speech understanding and to decrease reported hearing abilities among adults with sensorineural hearing loss and functional hearing complaints.

No study has systemically examined the relative efficacy of FM use and/or auditory training for veterans with mTBI and normal/almost normal hearing sensitivity. The effectiveness of these two intervention strategies will be examined in this study through a between-subjects randomized controlled clinical trial comparing the outcomes of: (1) FM use alone, (2) BFP alone, and (3) FM+BFP combined. All groups will also receive informational-counseling, as will (4) a control group. Outcomes will be measured subjectively through self-report of auditory competence.

The results of the study will help to determine whether or not the use of FM systems or auditory training, either alone or combined, are efficacious interventions for blast-exposed veterans with reported functional hearing difficulties and normal/near-normal auditory sensitivity. Results will contribute to the development of evidence-based auditory rehabilitation for these veterans, moving VA closer to fulfilling its goal of providing excellence in patient care, veterans' benefits and customer satisfaction.

Eligibility Criteria:
Inclusion Criteria:

Participants will be OIF/OEF veterans with no exclusions based on age, ethnicity, or gender. To be included in the study participants will:

* Report difficulty understanding speech in difficult listening environments disproportionate to loss in hearing sensitivity, as defined by self-referral to the study
* Have hearing thresholds \<= 65 decibels hearing loss (dB HL) at 0.5, 1.0, 2.0, 3.0 \& 4.0 kilohertz (kHz)
* Cognitive abilities sufficient to participate in the study, as determined by an age and education-level appropriate score on the Mini Mental State Exam (MMSE; Folstein, Robins, \& Helzer, 1983; Crum et al., 1993),
* English as a first language,
* Openness to using a personal FM system for a four-week period and/or to conducting auditory training over an eight-week period, as determined through interview.

Exclusion Criteria:

* Asymmetric pure tone thresholds (left-right difference \> 15 dB HL at frequencies of 500 through 4000 Hz),
* Presence of neurological, psychiatric or physical disorders, or co-morbid diseases that would prevent completion of the study as determined by chart review,
* Best corrected vision worse than 20/63 as measured with the Smith-Kettlewell Institute Low Luminance (SKILL) Card