Toward an improved hearing safety standard for impulse noise exposure in the Canadian Armed Forces

Abstract

Introduction: Current hearing safety standards for the Canadian Armed Forces (CAF) do not adequately address exposure limits for mitigation of noise-induced hearing loss (NIHL) from weapon noise. Recommendations for updating the hearing safety standard are being formulated by the recently initiated Noise Health Hazard Working Group (NHHWG). In this article, we aim to provide a way forward for the NHHWG. Methods: On the basis of experience with auditory research, noise measurement, acoustic standards development, interactions with CAF members, and a review of the literature, we present an overview of the current state of knowledge regarding impulse noise. The topics include impulse noise measurement, engineering and administrative controls for noise exposure, and use of personal hearing protection devices (HPDs). Results: Although technology for impulse noise measurements and ways to account for HPDs have improved substantially in recent years, not much has changed in hearing damage risk criteria. Energy-based metrics can account for the impulse duration and frequency-dependent characteristics of the HPD, which are important considerations in calculating allowed exposures. Discussion: The NHHWG is recommended to focus on measurements of current weapons systems in various configurations and training environments and to evaluate the use of energy-based metrics, together with frequency-dependent HPD insertion loss.