Invention May Make Air Travel Much Quieter
Membrane could block 1K times more sound energy than plane alone
By Arden Dier,  Newser Staff
Posted Apr 29, 2015 11:17 AM CDT
A rubber membrane can significantly cut down aircraft noise, researchers say.   (Yun Jing)
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(Newser) – Does the buzzing of a plane's engines drive you bonkers? Researchers have come up with a product that could save you some grief. They've developed a thin membrane capable of blocking low-frequency noise that tends to bounce around the cabin. The honeycomb-like material typically used on a plane's floor and ceiling—hollow cells sandwiched between two thin walls—is strong and lightweight, but it does nothing to protect passengers from outside noise. This new membrane, however, could be applied to one side of the existing structure to essentially make the plane soundproof, while adding just 6% to the weight of the honeycomb panel, which should have a minimal effect on fuel efficiency, a press release from MIT and North Carolina State University notes.

In a study in Applied Physics Letters, the researchers explain that low frequencies are able to penetrate porous materials or acoustic blankets often used in soundproofing. But "at low frequencies—sounds below 500 Hertz—the honeycomb panel with the membrane blocks 100 to 1,000 times more sound energy than the panel without a membrane," a study author says. Plus, the rubber material, which is just 0.25 millimeters thick, "is relatively inexpensive to produce, and can be made of any material that does not impact the structural integrity of the honeycomb panel," a researcher adds. "It could make flying much more pleasant for passengers—particularly in helicopters." (Too bad it can't block out all those farts.)