Cutting-edge technology developed by experts at Air Force Research Laboratory's human effectiveness directorate is being used with SpaceShipOne. The privately manned spaceship reached 328,491 feet (62.2 miles) for the second time in five days Oct. 4.

The spaceship crew used an attenuating custom communications earphone system. It allows clear voice communication while providing improved hearing protection for pilots, ground crews and almost anyone working in and around high-noise environments.

Today, pilots and ground crews must wear foam earplugs under communications headsets for hearing protection. This created communication problems because the foam plugs would muffle out all noise, including critical communication.

"(The earphone system) has solved this problem by integrating communications into a hearing protection earpiece customized for each user," said John Hall, an AFRL researcher. "The development of (the system) has revolutionized hearing protection for military applications as well as many commercial industries."

AFRL experts initiated the research because of a deficiency report posted by the F/A-22 Raptor program office. Maintainers had reported problems communicating with each other and with the cockpit when engines were in the higher power setting.

Mike Melvill, who earned astronaut status for flying a nongovernment sponsored vehicle more than 50 miles above Earth on Sept. 29, wore the earplugs aboard SpaceShipOne. He said he "couldn't have heard anything" without them.

"Before these plugs, we had problems because we were using little foamy earplugs," he said. "We had to drill a hole and push a microphone through, so it was a clumsy attempt to copy what (human effectiveness directorate experts) have done. These older ones were pretty noisy, and the reception wasn't all that great.

"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. "On both of those flights we recorded above 120 (decibels) in the cabin, and it felt ... like I was sitting right here; it was perfect. I am very, very pleased with how they work."

Viable applications for the new plugs exist in industrial and military environments. Directorate officials have been contacted to discuss applications for in-the-ear monitoring for motor sports, Mr. Hall said.

"It's useful anywhere that you're likely to find yourself in a high-noise environment and need to communicate," he said. "Current technologies that target communications in high-noise environments have limits. There are a lot of industries and military applications where you exceed those limits, so you need to ... get closer to the ear drum to provide optimal communication and optimal noise control."

Active noise reduction has been demonstrated on the F/A-22 aircraft to target higher noise environments. Other applications include petroleum drilling and mining, law enforcement, fire rescue, homeland security and nuclear chemical bio defense.

Future improvements will incorporate other technologies such as biosensors for monitoring human vital signs while in harsh environments and microphones for duplex communication. It will also incorporate natural hearing restoration which allows side-by-side conversations by selecting an ambient option.

"If you want side-by-side communication, and you don't want to go through the radio or the cockpit interphone system, you could cue one of the microphones on the outside of the device, and you'd be able to talk to each other," Mr. Hall said. "Right now, they can hear whatever comes through the avionics."