Hazardous noise and blasts are prevalent military occupational exposures that can result in adverse hearing outcomes among US military Service members and Veterans and have profound consequences on health and wellbeing. Significant knowledge gaps exist in understanding the burden of hearing loss and the associations between military exposures and hearing both during and after service. Moreover, little is known about the causal mechanisms that can explain these effects. Evidence that helps fill these gaps will aid the Departments of Defense (DoD) and Veterans Affairs (VA) in designing effective interventions and rehabilitation programs. The overall goal of this dissertation was to estimate: 1) the prevalence of hearing loss by severity; 2) rates of hearing changes during military service as a consequence of occupational noise exposure; and 3) mechanisms of the effect of blast exposure on self-reported hearing difficulty. These aims were designed to rigorously yield practically useful information with the goal of improving hearing health and guiding policy.