A Ring Tone Meant to Fall on Deaf Ears - New York TimesI wager this will work best in the pre-headphone age group -- probably under age 13. The interesting aspects of this are:
In that old battle of the wills between young people and their keepers, the young have found a new weapon that could change the balance of power on the cellphone front: a ring tone that many adults cannot hear.
In settings where cellphone use is forbidden — in class, for example — it is perfect for signaling the arrival of a text message without being detected by an elder of the species.
1. It sounds a lot like one of my favorite science fiction stories: Fast Times in Fairmount High.
2. The same technology that has allowed worldwide rapid dissemination of low cost weapon designs  has allowed the emergence and dissemination of this technology. Such things took far longer back in The Day.
The World's IQ, and particularly the effective IQ of youth, is rising. For better and for worse. Elders of the world, treat the young well. They may be vengeful ...
 So-called "IEDs", which are no longer "improvised" -- as well as recipes for building destruction).