"The device works by emitting a pulse at 17-18 kilohertz that switches on and off four times a second for up to 20 minutes. Teenagers can pick it up through minute hairs in their inner ears – but those hairs tend to die off by the time they reach 25."Don't miss the full text of the article, which has samples of the actual sound (which I can hear quite easily, though I'm supposedly too old).
Friday, February 22, 2008
Boing-Boing has a link to an article about an ultrasonic anti-teenger device in use in Britain.