Technology: Stethoscope for Jet Engines

From the earliest days of aviation, when the whistle of wind in guy wires gave the trained pilot as much information as any instrument, airmen have relied on their ears to recognize the sounds of trouble. Now the roar and whine of modern jets make it hard for the human ear to detect anything but the most obvious trouble. And by then it may be too late. To give pilots and maintenance a boost. General Electric is developing a sonic analyzer that can be applied to jet engines much as a physician's stethoscope is applied to the human chest....