Teenagers’ latest weapon in the fight to do SMS in the classroom: stealth ringtones. Based on the principle that people lose their auditory sensitivity to higher-pitched tones as they grow older, kids have been loading up phones with what are essentially dog whistles. Ironically, the technique was spawned by a device called the Mosquito, which was designed to drive teenagers out of stores while leaving adults unfazed. The stealth ringtones backfire when used in the presence of an adult who hasn’t yet lost (all of) their high-tone sensitivity. Techdirt has more.
A .wav sample of the tone can be “heard” here — totally silent to me.