T he U.S. Army

is evolving into an expeditionary force with periods of deployment interspersed with periods of home garrison training. The majority of recent deployments have been in relation to Operation Iraqi Freedom (OIF) and have involved battlefield scenarios and potentially volatile peacekeeping missions. Given the current military operations, the Army represents a unique noise-exposed and medically evaluated population of soldiers who may be at increased risk for noise-related health outcomes. The objective of this study was to establish a noise-induced hearing loss injury (NIHLI) prevalence baseline for a period of time including major unit deployments and units returning from deployments (redeploying) with noise exposures consistent with heavy combat operation