The escalating cost of claims for Noise Induced Hearing Loss (NIHL) in the Canadian Armed Forces (CAF) supports the need to review and upgrade current hearing conservation practices. The rise of these escalating costs and the need to protect the military personnel when training in extreme noise conditions has initiated an engineering investigation within the Department of National Defence (DND) and in collaboration with the University of Ottawa, to review the existing standards in the field of hearing protection test and evaluation, to propose technical recommendations and to identify the possible technical problems and gaps impacting the quality of the existing procedures. This study dealt with the estimation of the protection capability of Hearing Protection Devices (HPDs) in the case of high-level impulse noise from small firearms weapons that are a particularly damaging source of noise in military environments, representing an important cause of NIHL. Testing and evaluation based on a system engineering approach have been used in this work introducing: - A new testing approach, based on ANSI/ASA S12.42-2010, for testing HPDs when the impulse noise is generated by a small firearm; - A new evaluation approach for HPD performance, introducing a characterization approach using a sub-band analysis for dealing with impulse noise generated by a small firearm. The effectiveness of HPDs, taking into account the physiological human limitations induced by Bone Conduction (BC), is computed by using an innovative method attempting to better prevent the risk of NIHL when using small firearms.