A randomized controlled trial to evaluate approaches to auditory rehabilitation for blast-exposed veterans with normal or near-normal hearing who report hearing problems in difficult listening situations

Background: Blast exposure is a major source of injury among Service members in the Iraq and Afghanistan conflicts. Many of these blast-exposed veterans report hearing-related problems such as difficulties understanding speech in noise and rapid speech, and following instructions and long conversations that are disproportionate to their measured peripheral hearing sensitivity. Evidence is mounting that these complaints result from damage to the central auditory processing system. Purpose: To evaluate the effectiveness of audiological rehabilitative interventions for blast-exposed veterans with normal or near-normal peripheral hearing and functional hearing difficulties. Research Design: A randomized controlled trial with four intervention arms. Study Sample: Ninety-nine blast-exposed veterans with normal or near-normal peripheral hearing who reported functional hearing difficulties. Intervention: Four interventions were compared: compensatory communication strategies (CCS) education, CCS and use of a personal frequency modulation system (FM 1 CCS), CCS and use of an auditory training program (AT 1 CCS), and use of all three interventions combined (FM 1 AT 1 CCS). Data Collection and Analysis: All participants tested before, and immediately following an 8-week intervention period. The primary outcome measures upon which the study was powered assessed speech understanding in noise and self-reported psychosocial impacts of the intervention. In addition, auditory temporal processing, auditory working memory, allocation of attention, and hearing and cognitive self-report outcomes were assessed. Results: Use of FM 1 CCS resulted in significant benefit for speech understanding in noise and self-reported hearing benefits, and FM 1 AT 1 CCS provided more self-reported cognitive benefits than FM 1 CCS, AT 1 CCS, or CCS. Further, individuals liked and reported using the FM system, but there was poor adherence to and high attrition among individuals assigned to receive AT. Conclusions: It is concluded that a FM system (or remote microphone via Bluetooth system) is an effective intervention for blast-exposed veterans with normal or near-normal hearing and functional hearing difficulties and should be routinely considered as an intervention approach for this population when possible.