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Hear This -- or Better Yet, Don't

War is hell -- on your ears. Everything is a combat zone is death metal loud, from the props on the transport plane that takes you into Iraq to the rotors of the Black Hawk which hauls you from base to base to the sirens on the Humvee, keeping potential adversaries away. And that's before the bombs or the RPGs start going off. A buddy of mine lost 75% of his hearing in one ear when a bomb detonated nearby. The military has to shell out more than $300 million per year to compensate soldiers for their busted ear drums, according to one study.plug.jpgSoldiers are supposed to wear ear plugs at all times. But often, they don't. Makes hearing orders and warnings tougher, they say.The Air Force Research Lab has developed a pair of new jack, noise-cancelling ear plugs that might change some minds, however. The Attenuating Customized Communications Earpiece System (ACCES) was designed for the maintennance crews who work on the deafening F/A-22 stealth fighters.

The system filters out high-frequency noises from fighter aircraft while using tiny speakers to allow the wearer to hear radio communications.The real issue was the sound pattern around the F/A-22 was so loud, maintainers couldnt hear, said Hendrick Ruck, director of the Air Force Research Laboratorys human effectiveness directorate. With these, communication is almost perfect.The system makes use of several features to reduce noise.By being molded, (the ear plugs) have good passive protection, Mr. Ruck said. They are perfectly fitted. They also use active noise reduction. They take the predictable noises and cancel the wave forms.All fighter aircraft have high-frequency noise, Captain Kevin Divers, 27th Fighter Squadron aerospace physiologist, said. The plugs are made from silicone, which blocks out the higher frequencies while the form-fitted seal provides better protection from noises on the lower end...Our tests are pretty good, he said. (The ear plugs) canceled out 47 decibels in tests, which we think is a record.Larger ear protection devices and foam plugs, like those used now, only block out a maximum of 40 decibels, Mr. Ruck said...Along with the F/A-22, the system is being considered for helicopter pilots and special operations forces troops. It was used by civilian astronaut Mike Melvill aboard SpaceShipOne, the first manned, private spaceship that made history with its voyage into space.Before these plugs, we had problems because we were using little foamy earplugs, Mr. Melvill said.When I switched to the new system, I had perfect hearing of what was going on from mission control throughout both of my flights and had no discomfort at all from the noise of the rocket motor, he said.
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