Creare is actively developing technologies to improve the hearing protection available to military personnel. Some of these technologies are likely to have future application in industrial and commercial settings.

Protection from Extreme Noise

Navy flight deck and Air Force line crews work in a very challenging noise environment. Sound levels, which approach 150 dB for high-performance jet aircraft like the new Joint Strike Fighter (JSF), can cause hearing damage and impair communications. Hearing damage is now a common problem among today’s aircraft maintenance crews, which affects job performance and is the most costly Department of Defense disability (greater than $400 million per year in direct payments alone). Improved hearing protection is required to enable flight deck and line crews to work safely at optimum performance levels.

In addition to noise protection, crew headgear must address a variety of other requirements. Equipment and aircraft pose risks of cranial injuries from bumps or falls. Night operations require the use of night vision goggle (NVG) systems, which must remain fixed relative to the head to be effective. The threat of chemical, biological, or radioactive attacks mandates rapid donning of protective gear, including masks and hoods. Operational environments include tropical, desert and polar conditions. Uncomfortable helmets lead personnel to attempt modifications, which further reduces the helmet’s effectiveness. Heat buildup and excessive noise result in distraction and fatigue.

Creare has designed a helmet-integrated hearing protection system that is based on the knowledge gained from a test program using innovative evaluation techniques to understand how to best protect the head from extreme noise levels, and in particular, how to attenuate the transmission of bone-conducted sound. In that test program, we relied on rapid prototyping techniques to develop helmet shells with good sound attenuation characteristics and tested various combinations of commercial-off-the-shelf hearing protection components. A result of that test program is that our solution is layered and modular for the most comfortable and user-friendly design allowing for the addition of optional features or future capabilities as required. For the design noise levels, we have developed a baseline design helmet/headset system that combines modified commercial components using the existing technological base coupled with expendable deep insert earplugs (although our design can also use custom-molded earplugs if desired) to achieve the highest air- and bone-conducted noise reduction levels. As earplug use and fit are difficult to monitor and enforce, our helmet/headset system will provide the maximum noise attenuation possible using purely passive methods to reduce the need for bulky and costly electronics and electro-acoustic components that would introduce the potential for unacceptable failures during use in the harsh field environment.