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Frederick Gallun
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Central Auditory Dysfunction After Exposure to High-Intensity Blasts

by: Frederick (Erick) Gallun, PhD

Research Investigator, VA RR&D National Center for Rehabilitative Auditory Research, VA Portland Health Care System, Portland, OR


Associate Professor, Department of Otolaryngology/Head & Neck Surgery and Neuroscience Graduate Program, Oregon Health & Science University, Portland, OR



Over the past decade, one of the core questions concerning both our laboratory and others has been the extent to which the central auditory system is vulnerable to damage from physical forces external to the body, specifically the effects of blast-induced pressure waves on the brain (for a full review and complete references, see Papesh and Gallun, 2015). Both animal and clinical research in shows that visible damage to the auditory cortex and brainstem can impair auditory function. What we wanted to know was the degree to which damage that could not be observed using medical imaging could also lead to auditory dysfunction. This question became of clinical relevance when the VA and military hospitals in the US began to see a large number of individuals with auditory complaints and yet presenting with normal audiograms, which is the clinical gold standard for peripheral auditory function.


At the VA RR&D National Center for Rehabilitative Auditory Research and the Walter Reed National Military Medical Center, a cohort of blast-exposed service members was tested on a standard clinical battery for assessing central auditory dysfunction. We found that blast-exposed participants were significantly more likely to perform abnormally on temporal processing tests and tests of competing speech than were age- and hearing-matched control participants (Gallun et al., 2012). These results were replicated on a group of Veterans with a history of blast exposure who were tested an average of 8 years after exposure (Gallun et al., 2016). These behavioral results have been corroborated using electrophysiological measures in our lab (Gallun et al., 2012) and others (Saunders et al., 2015; Bressler et al., in press), and have also been found in patients with non-blast-related mild traumatic brain injury (Turgeon et al., 2011; Hoover et al., in press).


The future needs for this work are squarely in the arena of the members of ARO. It is crucial that animal models already existing for blast exposure and mild brain injury are used to test auditory function as well. There are no laboratories pursuing this work. Similarly, the imaging technology that exists for revealing dysfunction has not been applied to patients with known auditory dysfunction. If any members of ARO wish to pursue this important work, I would encourage them to contact us or others working in this area. The need is real and the opportunity is clear!





Bressler, S., H. Goldberg, and B. Shinn-Cunningham, Sensory coding and cognitive processing of sound in Veterans with blast exposure. Hearing Research, in press.

Gallun, F.J., A.C. Diedesch, L.R. Kubli, T.C. Walden, R.L. Folmer, M.S. Lewis, D.J. McDermott, S.A. Fausti, and M.R. Leek, Performance on tests of central auditory processing by individuals exposed to high-intensity blasts. J Rehabil Res Dev, 2012. 49(7): p. 1005-25.


Gallun, F.J., M.S. Lewis, R.L. Folmer, M. Hutter, M.A. Papesh, H. Belding, and M.R. Leek, Chronic effects of exposure to high-intensity blasts: Results on tests of Central Auditory Processing. Journal of Rehabilitation Research and Development, 2016. 53(6).

Hoover, E.C., P.E. Souza, and F.J. Gallun, Auditory and Cognitive Factors Associated with Speech-in-Noise Complaints following Mild Traumatic Brain Injury. Journal of the American Academy of Audiology, in press.


Papesh, M.A. and F.J. Gallun, Auditory impacts of Blast Exposure. Hearing Health & Technology Matters, Pathways: Neuroaudiology and Central Auditory Processing Disorders, F. Musiek, Editor. 2015.


Saunders, G.H., M.T. Frederick, M. Arnold, S. Silverman, T.H. Chisolm, and P. Myers, Auditory difficulties in blast-exposed Veterans with clinically normal hearing. J Rehabil Res Dev, 2015. 52(3): p. 343-60.


Turgeon, C., F. Champoux, F. Lepore, S. Leclerc, and D. Ellemberg, Auditory processing after sport-related concussions. Ear and Hearing, 2011. 32(5): p. 667-670.


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