Exposure to high levels of gunfire impulsive noise is potentially hazardous to human hearing and may lead to permanent auditory as well as non-auditory damage in the unprotected ear. Correctional Service Canada (CSC) approached NRC Aerospace to address a concern for potential hearing damage from discharging of firearms within enclosed spaces such as armoured control posts.

In order to address this concern, a reconfigurable control post was built by NRC on a shooting range and this test setup used to measure the impulsive noise time trace waveforms. The measured waveforms were analyzed in accordance with the updated standard procedure MIL-STD-1474E (revision 15 April 2015) using the algorithm suggested by the standard: Auditory Hazard Assessment Algorithm for Humans (AHAAH). This algorithm enabled the assessment of the auditory hazard risk to which personnel would be exposed during a Colt C8A2 carbine discharge. Three different geometry and floor area control post configurations were considered. Moreover two different control post window configurations where considered, namely: a) armored window with a narrow slit gun port opening surrounded by ballistic glass and b) wide open large window.

The paper presents the results and conclusions of the data analysis of the testing campaign aimed at evaluating the noise exposure and assessing the auditory hazard of personnel using the Colt C8A2 carbine.