A noise that annoys.

Rowdy teens used to hang out in front of the Spar convenience store in Barry, Wares. According to the store's owner, Robert Gough [rhymes with "tough"), they intimidated other customers and "they'd be in the shop fighting, stealing, and assaulting the staff." So Howard Stapleton, a security consultant, offered to let Gough try his invention: the Mosquito. This small electronic box emits a pulsating squeak at a frequency usually inaudible to anyone over 30. At first, the kids begged Gough to turn off the noise; then they left. "It's loud and squeaky and it just goes through you," says one 15-year-old. The device has not been tested by hearing experts, but Stapleton says, "I didn't want to make it hurt; it just has to nag at them." This wasn't the first time that store owners have used sounds to keep young people away. In the U.S., Canada, and the U.K., some 7-Eleven stores choose high culture over high-tech: loudspeakers blasting classical, music and opera.