A Ring Tone Meant to Fall On Deaf Ears.

This article reports that teenagers in the U.S. and the U.K. are equipping their cell phones with ring tones that, due to a decline in the ability of adults to hear high-pitched sounds, cannot be heard by persons of roughly 30 or more years of age. The tones have been adapted from a British invention that was used to deter teenage loitering in public places.