How Audiologists and Researchers Are Shaping Military Hearing Health Practices

In parallel with the WAHTS development, Creare received funding from the DoD to support the NMASC in developing an open-source, tablet-based software called TabSINT to facilitate hearing studies across the DoD. TabSINT made it possible for Douglas S. Brungart, PhD, chief scientist at the NMASC, and his team to conduct studies with thousands of active-duty subjects focused on hearing health, Dr. Clavier said. “Studies included, for example, the development of a new evidence-based hearing test based on operational performance—the Military Operational Hearing Test; the relationship between exposure to low-level blast and difficulty hearing speech in background noise; and deploying boothless audiometry during the COVID-19 pandemic,” she said.

Scientists at MIT Lincoln Laboratory (MITLL) developed a noise dosimeter capable of measuring both low-level blast noise, which is undetectable by commercially available dosimeters, and continuous ambient noise. MITLL partnered with Creare to customize the prototype, and Creare later received a new SBIR grant from the Defense Health Agency to produce this device, Dr. Clavier said. Working with MITLL and NMASC to test this device, Creare is starting low-rate production so early adopters in the DoD can begin using it. “There is significant interest within the Special Forces community because of the connection between repeated exposure to low-level blast and brain injury as well as hearing injury,” she noted.

A variety of studies have focused on understanding the threat of repeated low-level blast exposure during routine training with high-caliber weapon systems. “These studies require an extensive data collection effort on military training ranges involving researchers with expertise in hearing, cognition, neuroscience, engineering, and blast physics,” Dr. Kulinski said. “Research to date has highlighted hearing as a sensitive endpoint, including a dose-response model for predicting transient results for a given level of exposure and a standardized test battery and procedure for performing these types of prospective human subject studies (J Acoust Soc Am. doi:10.1121/10.0036149; Mil Med. doi:10.1093/milmed/usad299).”

“Still, much work is needed to improve our prediction of the long-term effects that are likely to result from repeated exposures, and the factors that might influence the risk that a given service member may experience hearing damage from a given noise event,” he said.

Long-Term Studies

Large-scale studies like the Noise Outcomes in Servicemembers Epidemiology (NOISE) study originally focused on collecting normative data (https://www.noisestudy.org). Since the development of the Military Operational Hearing Test—an auditory fitness-for-duty test adopted by the Army as the standard test for evaluating the functional performance of soldiers with hearing loss—research expanded to other aspects of hearing loss, according to Dr. Kulinski. A major contribution involved the collection of large-scale normative data from questionnaires and clinical tools for evaluating service members with hearing issues. For instance, results from the Tinnitus and Hearing Survey, administered to nearly 22,600 service members with varying degrees of hearing loss, help clinicians determine when self-reported hearing difficulties in individuals with normal or near-normal thresholds warrant clinical intervention (Trends Hear. doi:10.1177/23312165231198374), he said.