Teenager Repellant

A new gadget repels gangs of teenagers by emitting a high-pitched noise that can be heard only by people under their 20's. Police are backing the Sonic Teenager Deterrent, nicknamed the Mosquito because of its sound, reports the Daily Telegraph. It annoys teenagers so intensely they have to clutch their ears. Eventually they can stand it no longer and have to move on. But because the body's natural ability to detect some frequency wave bands diminishes almost entirely after 20, adults are completely immune. The black box sends out 80-decibel bursts of pulsing sounds at up to 16khz. It sounds to youngsters like a demented insect or a very badly-played violin. "The beauty of it is that the noise does not have to be loud, just pitched at the right level which affects teenagers."