A high frequency ringtone, known as “Teen buzz” is a tone too high for most adults to hear, making it a popular ringtone for teens who want to evade classroom rules by sending and receiving text messages and other communications in class. Ironically, the high frequency ringtone represents the creative adoption of a ploy that was designed to repel youngsters from loitering in commercial areas.

A security company located in the U.K. came up with the idea of installing a device that would emit a high-pitched buzzing noise that shopkeepers could turn on to keep youngsters from congregating outside their shops. The noise would not disturb adults, who would be unlikely to hear it. Compound Security called the device the Mosquito.

The Mosquito led to unexpected consequences when creative teens decided a high frequency ringtone would be perfect for surreptitious communications in class where cell phones are supposed to be turned off. Suddenly high-pitched whines were being sent from cell phone to cell phone, spreading like fire.

The high frequency ringtone escapes notice of most adults because as we age the human ear develops a condition known as presbycusis, which results in the inability to hear high-pitched tones. The high frequency ringtone registers somewhere between 14 and 17 kilohertz, making it inaudible to many, but not all adults.

Reportedly, creator of the Mosquito, Howard Stapleton of Security Compound, was alerted to the craze by daughter Colleen who showed him an article on the phenomenon. Stapleton has admitted to being amused by the ingenuity, though the high frequency ringtone used by teens is a constant 14.4-kilohertz, while the Mosquito is a modulated 17-kilohertz high frequency ringtone, says Stapelton.

According to many reports, teachers have already been subjected to dealing with the high frequency ringtone in class. In some cases children themselves tip off the teacher by laughing as a phone rings out. At least one teacher reported it was hard to be “cross” at such “resourcefulness.” Once the high frequency ringtone is no longer novel, however, it is likely to be less amusing. A silent ringtone opens the door to texting during tests and cheating, possibilities not nearly as lost on teachers as the high frequency ringtone that makes them possible.