Blast Exposure and Auditory Processing

By Frederick J. Gallun, Elizabeth G. Haley, Lindsey E. Jorgensen, and Sheila R. Pratt

This article is a part of the March/April 2020, Volume 32, Number 2, Audiology Today issue. Auditory problems are the most common service-connected disability (U.S. Department of Veterans Affairs, 2019) and the fourth leading cause of medical referral for Veterans of the United States military (McIlwain et al, 2008). Although it is established that noise exposure is one of the major causes of hearing loss and auditory difficulties in Veterans, the recent conflicts (Operation Iraqi Freedom, Operation Enduring Freedom, and Operation New Dawn) have drawn the attention of clinicians and researchers in the Departments of Veterans Affairs (VA) and Defense (DOD) to another significant risk factor for listening difficulties: exposure to high-intensity blasts (Gallun et al, 2017). Improvised explosive devices, rocket-propelled grenades, and mortars used in modern warfare produce incredibly powerful explosions with associated high-intensity noise. They also are responsible for some of the most serious injuries observed in the contemporary Veteran population. In addition to limb amputations and traumatic brain injury (TBI), multiple parts of the auditory system also are susceptible to damage from these blasts. Subsequently, auditory injuries are the most common single type of injury consequent to blast exposure, resulting in tympanic membrane perforation, middle-ear, and/or cochlear damage (Gondusky and Reiter, 2005). Gallun et al (2012) reported that U.S. Service members hospitalized after blast injury had a three-fold higher chance of abnormal performance on one or more tests of auditory processing relative to a control group matched in age and relatively minor differences in audiometric thresholds. Tests of competing speech and temporal processing were the most likely to be abnormal in this population.