Boeing scientists are working to eliminate unwanted noise with an active wall coating that uses compressed air

BY WILLIAM COLE

Imagine a high-tech "wallpaper" that uses compressed air to block out noise in a commercial or military airplane, protect sound-emitting military equipment from detection in the field, or shield sensitive satellites from deafening rocket sounds.

Such a solution is not so off-the-wall.

Scientists at Boeing are working on a technology that could actively suppress unwanted noise inside airplanes and even make life more comfortable for astronauts in space. The technology called "fluidic wallpaper" has many potential applications for protection, privacy and stealth.

Anders Andersson, a Technical Fellow at Phantom Works in Seattle, said the system promises to be "a breakthrough in acoustics technology."

The quarter-inch-thick wallpaper is an active-control system using "smart" materials. It employs compressed air to counterbalance oscillating pressures that make up low-frequency noise. Low-frequency sound is emitted by such commonplace systems as propellers, jet engines, and heavy-duty diesel engines, and is easily transmitted through walls and windows. Reducing aircraft engine low-frequency noise has traditionally commanded heavy-weight solutions — layers of sound-suppression materials that give the vehicles unwanted pounds and cost.

Fluidic wallpaper weighs much less than traditional materials, takes up less space and can be produced inexpensively. The compressed air used within the wallpaper is generated by aircraft engines or air conditioning and does not require electrical power.

The wallpaper is projected to be unmatched by any other concept in its low-frequency noise performance, said Andersson.

"We're still in the development stages and there's a lot more testing to be done," said Andersson, who is helping Boeing Commercial Airplanes in its efforts to control noise aboard commercial jetliners. But he already foresees plenty of other applications.

Fluidic wallpaper could be used, for example, as wall trim in commercial airplanes, and in executive airplanes and military transports to satisfy command-post communication and stealth requirements. It could muffle the noise of armored vehicles and improve communication and the quality of life for astronauts aboard the International Space Station. The system could be built into equipment tarps that would shield the outside world from noisy generators and other equipment and prevent their detection in military operations. It could be used also to line rocket fairings to protect sensitive satellite payloads from the effects of noise generated by a launch.

Andersson said, "There is potential for building a whole industry around this concept."