Young people buy ring tones you can't hear ...
By YUKI NOGUCHI and KIM HART

When it came out in Britain in December, the Mosquito sound system was supposed to be the sonic equivalent of a "No loitering" sign. Its annoying, high-pitched sound - which many adults can't hear but most young people can - would act as a teen repellent.

Now, teens are staging a worldwide rebellion: Downloading the sound, or another ring tone in that same high-frequency range, allows them to hear their cell phones ring when their parents and teachers (mostly) cannot.

And the company that brought the Mosquito to market - Compound Security Systems Ltd. of Britain - is being barraged by a new market of companies wanting to sell a line of subversive ring tones.

"When we brought out the teenager repellent to market, we really didn't think anybody would be interested in ring tones" in the same frequency, said Simon Morris, marketing and commercial director for Compound Security, who has been fielding hundreds of calls from companies and journalists around the world since the annoying ring tone became popular.

The original Mosquito device is a small black box that looks like a speaker and emits pulsating sounds at a frequency around 17 kilohertz - audible to relatively undamaged young ears but generally harder to hear for those older than 20.

"The human ear is responsive to a range of pitches, and that range gets smaller in the higher pitches with age," particularly when one has been exposed to loud noise for long periods of time, said Vic Gladstone, an audiologist and chief staff officer at the American Speech-Language-Hearing Association in Rockville, Md.

The appeal of a kids-only technology quickly caught on: Teens worldwide now use it to dodge cell phone restrictions in class.

The craze started a few months after Mosquito launched, when someone - probably in Scandinavia, according to Morris, though the British press pinned it on teens in Wales - designed software that allowed people to download a similar high-pitched sound to their phones, then share that ring tone with others by beaming it through a Bluetooth wireless connection.

Compound Security released its own version, and the Mosquito tone took on the classic attributes of viral marketing.

About a month ago, traffic on Compound Security's Web site spiked, as 100,000 kids tried to download the sound, Morris said.

Now, ring-tone sales sites such as Fork.com are hawking "the official Mosquito Ring tone" for $2.99 to compatible cell phones.

It hit the mainstream media this week, with stories in the New York Times and newspapers in Australia and Britain, as well as an appearance on NBC's "Today" and ABC's "Good Morning America."

Blogs have lit up on the subject of the ring tone, with many adults writing to say they can hear the high-pitched sound - though apparently not as piercingly as school kids can.

Gladstone, who has been monitoring the health of young people's hearing for years, said, "It's harder and harder to find healthy young ears."

But he notes that parents can look on the bright side: "If kids want to be able to take advantage of their good hearing, then they need to protect their own hearing."

Compound Security, which plans to start selling the Mosquito system through its U.S. distributor next month, hasn't gotten many complaints from teachers or parents about its alternative use, Morris said.

After all, teens are already able to set their phones to vibrate to escape notice, he said.