MOSQUITO RINGTONES
Inventor Howard Stapleton, creator of the Mosquito "teen repellent", says only a few people over age 30 can hear the Mosquito's sound. The "Mosquito's sound is a 17 kilohertz high pitched sound simialr to a mosquito buzzing. The intent of the sound is to emit a sound that is so annoying to teens, they would avoid the high pitched area and move on.
Teens have since taken the idea and created the mosquito ringtone that most adults can't hear. This allows "kids with phones" the opportunity to leave their phone on at school without the adults knowing weather the phone is ringing or there is an incoming text message.