Noise Attenuation of the HGU-56/P Aircrew Integrated Helmet System When Worn with the Combat Vehicle Crewman Hood (BALACLAVA)

摘要

The HGU-56/P Aircrew Integrated Helmet System (AIMS) is designed to provide impact protection and noise attenuation to U.S. Army rotary-wing aircraft crewmembers. The ability of any helmet to attenuate environmental noise depends on an adequate seal between the earcup and the user's head. Any object (e.g., eyeglass frames) or practice (e.g., loose chin strap) that interferes with the seal between the earcup and the head will compromise both helmet retention (with resultant effects on impact protection) and noise attenuation. The noise attenuation of the HGU-56/P AIMS was measured with and without the flight approved balaclava (combat vehicle crewmember hood). The balaclava interferes with the earcup seal and adversely affects the noise attenuation of the MGU-56/P AIMS. When worn without the additional hearing protection provided by earplugs or the Communications Sarplug, the balaclava can significantly affect operational capabilities. Results obtained from using minimal fitting instructions did not differ from those obtained using the ANSI Sl2.6-l997 Experimenter-supervised fit method. Care must be taken to fit the flight helmet correctly in order to ensure adequate noise and impact protection.