Auditory difficulties in blast-exposed Veterans with clinically normal hearing

Vast numbers of blast-injured Operation Iraqi Freedom/Operation Enduring Freedom/Operation New Dawn personnel report postconcussive symptoms that include headache, dizziness, poor memory, and difficulty concentrating. In addition, many report hearing problems, such as difficulty understanding speech in noise, yet have no measureable peripheral auditory deficits. In this article, self-report and performance-based measures were used to assess 99 blast-exposed Veterans. All participants reported auditory problems in difficult listening situations but had clinically normal hearing. Participants' scores on self-report questionnaires of auditory difficulties were more similar to scores of older individuals with hearing impairment than to those of younger individuals with normal hearing. Participants showed deficits relative to published normative data on a number of performance-based tests that have demonstrated sensitivity to auditory processing deficits. There were several measures on which more than the expected number of participants (15.9%) performed one or more standard deviations below the mean. These were assessments of speech understanding in noise, binaural processing, temporal resolution, and speech segregation. Performance was not universally poor, with approximately 53% of participants performing abnormally on between 3 and 6 of the 10 measures. We concluded that participants exhibited task-specific deficits that add to the evidence suggesting that blast injury results in damage to the central auditory system.