Insertion Loss of the HGU-84/P Rotary-Wing Helmet System with Oregon Aero Earcup Replacement Products

摘要

The sound attenuation of the H6U-84/P Rotary-Wing Helmet System with Oregon Aero earcup replacement products was evaluated in accordance with ANSI s12.42-1995 (R1999) Microphone-in-Real-Ear procedures. The differences in insertion losses between the various helmet modifications were generally quite small and unlikely to have an effect on operational considerations, especially if double hearing protection in the form of earplugs, the Communications Earplug (CEP), or Attenuating Custom Communications Earphone System for Aircrew (ACCES for Aircrew) is employed. The insertion loss of the helmet with the Oregon Aero HushKit earcup replacement foam was significantly poorer than the standard helmet system. Insertion losses with the SoftSeal (replacement earcup seal) with HushKit and the SoftSeal/HushKit Combo (soft replacement earcup) were statistically significantly greater than the standard helmet configuration at some frequencies, although the differences were marginal at the low frequencies at which rotary-wing noise hazards are the greatest. Caution is urged when considering the use of the SoftSeal or SoftSeal/HushKit Combo since, at the time of this writing, neither of these earcup replacement products has been evaluated for helmet retention or blunt impact protection in case of an aircraft mishap.