AN ELECTRIC EAR.

New Zealand Herald, Volume LXVIII, Issue 20768, 10 January 1931, Page 7 (Supplement)

AN ELECTRIC EAR.

HOW TO SUBDUE NOISES.

An electric ear, with which engineers hope to reduce noise by setting one sound to kill another, has been demonstrated at the Westinghouso research laboratory by Mr. J. P. Foltz, who developed it, says our New York correspondent. Ilis method of noise abatement consists merely in causing two sound waves to interfere. The chief obstacle Mr. Foltz encountered has been the inability of the human ear to separate complex noises sufficiently for him to discover which one to set against the other. The electric ear promises to overcome this handicap. Weighing 601b5., its method of attaching to and listening to a noisy machine is thus explained by its discoverer:—"When tho apple hits the floor, the impact starts a series of complex broadcasts which, in physics, are represented by waves, called sound waves. It is entirely possible to produce silence l>v two sound waves which fit each other, much like the teeth of two saw blades. " In a somewhat different application, it is also hoped that in the future this now portable ear may be used as an advance fault-finder for aeroplane motors and propellors. " So much more sensitive than the human ear, it is anticipated that it will hear loose wrist pins, piston rings, main bearings, warped or split propellors, long before they are loud enough—and consequently dangerous—to be heard by the human ear, " This future ear could be installed in an aeroplane's dashboard, so that a bad motor part or propellor blade developing during (light would instantly show up as a red light to warn the pilot of prospective trouble. Of course, these are only hopes at present." DIVERS' SAFETY SUITS. British submarine crews are being equipped with safety suits, in which it is possiblo to remain alive under water for about two hours. On the surface the dress acts as a lifebuoy. In the breast of the suit is a tube filled with oxygen. In an emergency tho wearer puts in his mouth a pipe connected with the oxygen supply, turns a tap, and inhales. A face protector closes the nostrils. The crew would then open the hatch of the submarine and float to the surface. TO HEAT 100,000 KETTLES. The Metropolitan-Vickers Company have just made at Trafford Park, in Manchester, and installed at Portishead near Bristol, a wonderful electrical machine, the most, powerful generator yet made by a British firm. It would heat 100.000 kettles, work 250,000 vacuum cleaners, or light 1,250,000 lamps. Tho whole turbo generator _of which it is a part is rated at. 50,000 kilowatts, tho equivalent of 67.000 horsepower, and is equal to 750.000 men, or about 25 of the most powerful type of locomotives. Trafford Park, once the home of the De Trafford family, through whoso grounds the Ship Canal was dug, is now famous for its electrical machines. Tho streets in this area are laid out on the American plan, and have numbers instead of names. BED OF THE PAOIFIO. In a report before the Geographic Society of America, which met at the University of California recently, Dr. Jerry Byerley stated that computations on the basis of earthquake records during tho last eleven years give the probable thickness of the earth's surfneo layer beneath the Pacific as about 25 miles. Ilis measuring rod was the so-called Love type wave, which characterises the beginning of tho end of every earthquake Its vibrations travel through the surface of tho earth from the site of the disturbance, shaking the layer of rock as. a series of hammer blows would shako the steel of a tank. Tho relationship of velocity to wave length varies with the thickness of the layer of rock through which the waves travel.