Breakthrough Earplug Protects Hearing and Boosts Communications Published May 21, 2009 By Maria Callier AFOSR ARLINGTON, Va. -- AFRL-sponsored research has led to an earplug that not only revolutionizes hearing protection for Air Force (AF) pilots and flight crews, but could meanwhile improve their radio communications. The groundbreaking research, led by Dr. Laura Ray (Dartmouth College Thayer School of Engineering), generated a novel earplug design based on active noise reduction. The new device is expected to impact the work of active-duty soldiers by greatly diminishing acoustic noise (and the associated potential for hearing loss), as well as improving the clarity of audio speech transmissions. Dr. Ray solved the mathematical aspects of the technology, achieving the first-ever conjoinment of noise control algorithms in a highly stable, hybrid system. This scientific advance enables a much more robust approach to noise cancellation for the acoustically dynamic conditions encountered around aircraft engines. Beyond working out the math, another primary challenge was to develop an electronic module for the earplug--one that could operate for 15 to 20 hrs on AA batteries. In addressing this issue, Dr. Ray was able to leverage cutting-edge processor technology that consequently yielded the requisite lower-power module. Among the new earplug's many other built-in benefits are its high-fidelity audio (producing clear speech), wide frequency range (optimizing the usable spectrum), lightweight configuration (minimizing head/neck fatigue), and replaceable eartips (facilitating hygiene). Easily stored in a small pouch attached to an Airman's flight vest, the electronic module delivers communication signals through the earplugs, which are worn under the helmet. Having completed both design verification and operational evaluation, the first generation of this earplug has undergone flight test at more than a half-dozen AF bases. Accordingly, researchers anticipate a refined second-generation product that demonstrates additionally reduced power consumption, size, and weight, as well as acceptable compatibility with a new aircrew helmet. In the meantime, Dr. Ray continues to explore ways of improving the earplug's capacity to reduce noise and enhance communications. She plans to investigate a signal delivery method that enables the headset wearer to perceive his or her auditory environment as if using "natural" hearing, whereby the listener is able to better focus on certain sounds while tuning out distracting ones.