Noise Outcomes in Servicemembers Epidemiology (NOISE) Study: Design, Methods, and Baseline Results.

Objectives: Military Service members and Veterans commonly report hearing loss and tinnitus, both of which can result in significant disability. During military service, Service members are exposed to many different types of loud noise, which is strongly associated with hearing loss and tinnitus. Other military-related exposures, such as chemicals and traumatic brain injury (TBI), are also linked with auditory problems. The purpose of the "Noise Outcomes in Servicemembers Epidemiology" (NOISE) study is to gather information from Active-Duty Service members and recently separated Veterans about their military and nonmilitary noise exposures, other relevant military and nonmilitary exposures, and potential outcomes of these exposures including tinnitus, hearing loss, and other hearing-related health concerns.

Design: The NOISE study assesses lifetime noise exposures, chemical and blast exposures, TBI, physical and psychiatric comorbidities, and other military and nonmilitary exposures and outcomes that can affect auditory function. Participants undergo comprehensive in-person audiologic examinations; those who experience tinnitus undergo a complete tinnitus assessment. Exposures and select outcomes are reassessed annually by mail, and the comprehensive in-person assessment is completed every 5 years. This report presents descriptive, baseline data obtained from the first 690 participants enrolled between 2014 and 2018.

Results: Some notable findings from this analysis include: (1) the prevalence of hearing loss in the sample was 8% for low frequencies (0.25 to 2 kHz), 20% for high frequencies (3 to 8 kHz), and 39% for extended high frequencies (9 to 16 kHz); (2) the prevalence of tinnitus was 53%; (3) the prevalence of both hearing loss and tinnitus was higher among those with higher age, more years of military service, greater degree of noise exposure, and exposures to blasts and/or TBI in the military; and (4) tinnitus was most prevalent among participants who serve/served in the Army relative to the other military branches.

Conclusions: The NOISE study is acquiring comprehensive data on military-related auditory dysfunction. It is the first of its kind to enroll active Service members and recently separated Veterans into a longitudinal study to examine the etiology and outcomes of tinnitus and hearing loss in this population. Although these data do not necessarily represent the entire military and Veteran populations, ongoing enrollment is focused on increasing generalizability and will also provide the statistical power to conduct multivariable analyses. This will allow us to examine longitudinal associations of interest while controlling for potential confounders and other possible sources of error. These data will provide critical knowledge to refine future military hearing conservation efforts and inform efforts to develop future treatments.