Science: Noise Destroyer

People bothered by noise may get some relief through electronics. In the Journal of the Acoustical Society of America, Harry F. Olson and Everett G. May of Radio Corporation of America tell about a gadget that reaches out to kill sound waves before they hit the ear.

Olson and May connected an extra-sensitive microphone to an amplifier and a loudspeaker, which they placed directly behind the microphone. When a sound wave hits the microphone, the loudspeaker reacts in such a way that it increases or reduces the air pressure in its vicinity just enough to cancel out the sound wave. The result...