Some extra info....
Flight Deck Cranial (FDC) & Hearing Protection Devices (HPD)
http://www.dawnbreaker.com/about/pub...4_Profiles.pdf &
Adaptive Technologies, Inc.
"...Noise generated in and around military aircraft presents a significant risk to short and long-term hearing health and creates an environment in which communication becomes intractable....
...Today, there are tens of thousands of Aegisound hearing protectors incorporating ATI’s technologies aboard Navy ships. ATI also partnered with Lockheed Martin on its Joint Strike Fighter Program, and Lockheed Martin has purchased hundreds of Digital Active Noise Reduction (DANR) Double Hearing Protector (DHP) systems from Aegisound, which are designed to be used in extreme noise environments such as jet noise up to 140 dB(A)....”