European Stars And Stripes (Newspaper) - August 22, 1987, Darmstadt, Hesse                                New technology zaps unwanted noise by Williamj. Broad new York times science has begun to conquer noise dissecting it uncovering its secrets and deleting in with ingenious new devices. At the Hearl of the achievements is a 191h Century technique that Breaks noise into ils components enabling scientists to Cul through the Din of the auditory world to the individual strands that make up everyday sounds. Using computers and sensors scientists can now discern the distinctive signatures of faulty parts inside nuclear reactors or the Buzz of aggressive killer bees. They have Learned to single out and neutralize unwanted sounds fighting noise with an Inoise sound whose wavelengths Are exactly the opposite of the unwanted noise. This anti noise cancels out the oar of engines. The whine of Industrial fans and Power transformers and the throb of heavy machinery while leaving desired sounds Sharp and Clear. As the Cost of crucial parts especially semiconductor chips declines the methods Are Likely to turn up in consumer goods. We re on the verge of a new Era said Larry j Eriksson research director of Nelson Indus fies a company in Stoughton wis., that recently started making noise cancellation devices. In the next Century these techniques will be  Malcolm a Crocker chairman of mechanical engineering at Auburn University in Alabama said As electronics get cheaper and More sophisticated All kinds of unusual acoustic techniques Are becoming much More  Dwayne n. Fry head of reactor systems at she Oak Ridge National Laboratory in tenn., said advances in detecting sound were improving diagnostic skills in such areas As nuclear plants honeybees and the human  the theoretical basis Lor the strides was Laid in the Early 19lh Century by Baron Jean Baptiste Joseph Fourier French mathematician and confidant of Napoleon Bonaporte who discovered that any periodic oscillation can be broken Inlo a series of simple regular wave motions. His analytic tool the Fourier transform can be applied to sound Light or any wave phenomenon Fourier s analysis came Inlo ils own in the 1960s with the Advent of cheaper computers and the perfection of software to enable them to perform a form of the technique called the fast Fourier transform. Today a computer can slice a Complex noise Inlo 1,024 frequencies in a fractional a second revealing underlying harmonics. The method is comparable to looking at Waves on the surface of a Choppy windblown Lake and tailing that it had been disturbed by me splash of a fish. At the Oak Ridge National Laboratory which conducts Energy research Lor the , government Fourier analysis is advancing the Artol detecting Subtle noises in nuclear reactors indicating their health or problems. The technique Breaks apart an auditory signal and the results Aie charted on a graph in tha form of a curved line. The repetition of the process enables researchers to paint an Overall portrait of Normal and troubled reactors. Commercially such techniques Are being used to pinpoint Loose parts in Reader Cooling systems including nuts bolls and even tools left behind after construction or maintenance an unusual spinoff of such work is the ability to distinguish Between african sized. Or killer bees and Domestic ones. Now in Mexico and moving northward Al a rate of 200 Miles a year Africani Zed bees appear almost identical to Domestic species but Are much More aggressive and unpredictable. Previously they could be identified Only through examination by Microscope. But Oak Ridge researchers suspected that killer bees beat their wings at a different frequency than Domestic ones. So they tracked Down a Roar to muted by its Mirror image a now Way to Khiev quieting la to actively cancel unwanted noise with Mirror image sound wave or  Nasa is pm Merino the technique for use in quieting aircraft with experimental Turxtx top Jei end lines. Which Are wry fuel Elf Taeni but noisy. In part because propeller Blades turn Al supersonic speeds. A microphone Sampton the unwanted engine whine a computer analyses the noise and then creates its Mirror image which la Ted to a Loudspeaker in me a attn. The two sell of Waves continuously adjusted to be exert opposite cancel each other out wite desired noises such human speech Are in attested.  broken wot Ampf Fleder  analysis and tape recordings of Aln Cani de bees. Sure enough it stuck out like a sore thumb recalled Howard Kerr an Oak Ridge researcher who raises bees As a Hobby ii was a higher  in january Kerr and an Oak Ridge colleague Mike Buchanan. Went to Venezuela for a Field lest in identifying Africani Zed bees using Fourier analysis. The method proved so effective that the researchers Are racing to perfect a portable detection device hoping in will be marketed commercially and used to help track and control the bees spread in North America some of the most dramatic results of the new acoustic research Center on silencing unwanted noises. The essence of i he an Inoise technique is to measure the frequency of an unwanted noise using Fourier analysis and then to broadcast its Mirror image. The peaks of one wave coincide Wilh the troughs of the other cancelling each other out. It s a crazy thing to say you make twice As much noise and you can t Hearil observed Glenn e. Warnaka vice president of applied acoustic research in state College a but it works and there s no end in sight to the  the technique works on predictable noises such As the repetitive Roar of engines rotating machinery and fans. Microphones Sample the rhythm of the noise microchips design its Mirror image and the resulting anti noise is broadcast by loudspeakers or headphones. The method is useless against random noises such As those made by the human voice because they Are impossible to predict Fourier analysis plays a key role in noise cancellation because it isolates the periodic elements of target noise and ignores everything else. A tiny fraction of the desired noise May be cancelled but the effect is usually in delectable. The Bose corp., in Framingham mass., which makes audio products and loudspeakers is experimenting Wilh a special Headset meant to cancel unwanted Noisa in aircraft and Industrial settings while allowing Normal communications to continue unfettered. The system was tested by the pills of the ultralight aircraft voyager in their flight around the world without refuelling and it has been extensively studied by the biological acoustics Branch of the aerospace medical research Laboratory at Wright Zallerson air Force base in Ohio Nasa is investigating an Inoise techniques to quiet Cabins on air planes powered by fuel efficient but noisy Turboprop engines. The noise Levels in the cab Are about twice As High As " regular Jel a said Dovid g. Stephens an official in the acoustics division of the Nasa Langley research Center in Hampton a one an Inoise method now being tested he said is to put speakers inside the cab that counteract noise coming through the  another an Inoise goal is to silence the hum of electrical Power transformers and substations. The electric Power research Institute the research Armol the  electric Utility Industry based in Palo Alto Cahl formed an an Moiso team Early this year to study ways to fight substation noise. 1 it s a difficult problem because the transformers can go on Lor blocks said Selwyn e. Wright. A project manager for the Escaich Institute s electrical system division the alternate building Brick enclosures