Using the Auditory Hazard Assessment Algorithm for Humans (AHAAH) With Hearing Protection Software, Release MIL-STD-1474E

The Auditory Hazard Analysis Algorithm for Humans (AHAAH) calculates the risk to human hearing of impulse noises, such as gunfire or airbag deployment. It achieves this by modeling the effects of the sound pressure wave from the free field, through hearing protection (if used), through the middle ear, and into the inner ear. The output of the algorithm is the number of auditory risk units (ARUs) associated with exposure to the given impulse sound. ARUs predict hearing damage; values over 500 ARUs for a 24-h exposure are likely to produce permanent hearing loss. AHAAH can account for the use of many different forms of hearing protectors. AHAAH models the effects of the hearing protector on the sound pressure wave and evaluates the risk of hearing damage in ARUs when hearing protectors are properly worn. The algorithm is implemented in computer software. This report is a user s manual for the AHAAH software release MIL-STD-1474E. The original document contains color images.