Acoustic standards for high-level impulse noise

High-level impulse noise has been a significant source of hearing loss among active duty military personnel, veterans, law enforcement and recreational firearm users. The development of standards for estimating the risk of hearing loss due to such exposures is complicated by a lack of human exposure data. Following World War II, the Army Research Laboratory conducted a limited series of studies that led to the development of MIL-STD 1474, which was based on peak exposure level and envelope duration. In the late 1980s, the US Army recognized that large caliber weapons had different outcomes than small-caliber firearms. The Army conducted the Albuquerque Blast Overpressure Walk-up studies that led to extensive debate about how to estimate the risk of hearing loss from these sounds. The DoD Blast Injury Prevention Standards Recommendation Process evaluated several candidate noise exposure metrics including equivalent energy exposure, Auditory Hazard Assessment Algorithm for Humans, Integrated Cochlear Energy model, and Auditory Model 4.5. Weapon noise measurements were used to highlight how maximum permissible exposures provide a framework that relates the disparate predictions from the models.