Chris Fettig found something really kewl. It's a 2006 story from National Public Radio about a special high-frequency sound - which most teenagers can hear but not most adults - that storekeepers in Great Britain have been using to keep young people from loitering in their stores. Well, now the kids are using that same sound as a ringtone on their cellphones... which lets them know while in class that they've a text message. The teachers can't hear it but the teens can!
Well, supposedly adults can't hear this. Because I'm in my early thirties and I've heard it clear as a bell every time that I've played this: it's a very high-pitch buzzing sound that might give you a headache if you listen to it for too long. Want to try it for yourself? Take a listen to it right here!
