DAYTON, Ohio — The same kind of earplugs sold to Def Leppard, the Moody Blues, Nine Inch Nails and other rock bands are starting to be used by U.S. military pilots to protect hearing, muffle cockpit noise and ease communications.

Lt. Gen. John Bradley, chief of the Air Force Reserve, tested the earplugs himself when he flew F-16 jet fighters in December. Bradley was so impressed that he directed his staff to tap into unused funds to speed up purchasing the earplugs.

"These things are phenomenal," Bradley said. "It cuts out more noise, and I can hear much better. I want to buy this for every Reserve I have who wears a helmet."

Unlike commercial aircraft, military planes usually have no insulation in the cockpit to help muffle engine and wind noise. And the fans that cool cockpit equipment can be loud.

To protect against hearing loss, most pilots use foam earplugs designed to be disposable. Some pilots keep the plugs loose in the ear or cut the plugs in half so they can hear the speaker in their helmet used to communicate with their crew and other pilots. Or they crank up the volume on the speaker so it can penetrate the foam plug.

The new earplugs originally were developed for aircraft maintenance workers who often had to stand next to deafening jet engines.

"The pilots got jealous," said John Hall, audio engineer in the Air Force Research Lab at Wright-Patterson Air Force Base.

The lab has been working on the plugs with two private contractors: Manufactured Assemblies Corp. of Dayton and Westone Laboratories Inc. of Colorado Springs.

The earplugs are similar to the ones that Westone sells to rock bands, said Karl Cartwright, head of new product development for the company. Musicians use the plugs not only to protect their hearing, but also to hear the sounds of the individual instruments and voices more clearly.

The new plugs are made of silicone, with speakers implanted inside. Each plug is designed to fit the ears of individual pilots and has small vents that relieve pressure created with changes in altitude that can rupture eardrums.

About 300 pilots and maintenance workers are using the new plugs, he said. They cost more than $200 a pair, while the old foam plugs cost a tiny fraction of that and are thrown away after use.

Bradley and Hall believe the new plugs will save money in the long run by reducing hearing loss and disability payments to pilots and maintenance workers. The Department of Veterans Affairs made 384,000 hearing-disability payments in its 2004 fiscal year, including 85,000 payments for complete hearing loss.

Military analyst Loren Thompson of The Lexington Institute, a think tank based in Washington, D.C., said the new plugs seem like a sensible investment.

"This is a relatively cheap invention that pays big dividends," Thompson said. "The Air Force spends the better part of a million dollars training each pilot, and it loses a percentage of those pilots to service-related disabilities such as hearing loss."