Mosquito Ringtone, also called Teen Buzz is a 17khz high frequency sound which can be heard by teenagers but not adults due to presbycusis (a normal loss of acute hearing that occurs with advancing age). It has now become a popular ringtone that was hijacked from the technology that was originally used to repel loitering teenagers from congregating at shops or parking lots in the United Kingdom. Techo-savvy choolchildren have recorded the sound and spread it from phone to phone via text messages and Bluetooth technology. It's been showing up in classrooms all over the world.
Click here to free download Mosquito Ringtone Mp3. Link to the NYT article Link to Teen Buzz on Wikipedia Another link(right click and save as) to download the high-pitch alarm.