Mosquito-like sound works as a teen repellent

Jodi McFarland | By Jodi McFarland | The Saginaw News
on April 04, 2008 at 8:30 AM, updated April 04, 2008 at 3:26 PM

Switch on the small gray metal box and listen: A sharp, pulsating, high-pitched tone burrows into the ear like a power drill bit, prompting an agitated, please-shut-that-blasted-thing-off grimace.

You hear that if you're between the ages of 13 and 25. If you're not, you may not sense a thing.

Can you hear them? Listen for yourself here:
Mosquito ring tones.

Howard Stapleton himself can't hear the sound he conjured up three years ago after a store owner told Stapleton that he and other merchants and customers wanted the young toughs who harassed customers gone, but feared a confrontation.

As the 41-year-old security device inventor from Wales contemplated the problem, he recalled from his teenhood the awful buzz of an ultrasound welding machine at his father's glue-plastics factory. He remembered that his complaints was met with a quizzical look from workers: "What noise?"

From that impulse to help rid his local market of loiterers came his invention, "the Mosquito," an electronic contraption that emits a high-pitched pulsating sound mostly heard only by teens and people in their early to mid-20s.

It works because an age-related hearing loss called presbycusis reduces the ability to hear high-pitched sounds after the late 20s. The device is mostly inaudible to older adults, young children and pets.

The Mosquito emits a sound for up to 20 minutes that's heard up to 60 feet away. It's heard through earphones and over loud music. It is for commercial and official use only, the manufacturer says.

Young people, meanwhile, have turned the table on the technology. Many have downloaded the sound onto their cell phones, creating a ring tone that they can hear but older adults can't. Teen Buzz, a short Mosquito ring tone, has become among the most downloaded ring tones worldwide. Some use it to alert high school classmates of recently sent text messages. For others, it's come in handy when parents curtail use of their cell phones.

The device has helped with youth crowd control at a school system in Columbia, S.C. Rick McGee, emergency services manager at Richland School District Two, said the schools put one Mosquito in a vehicle and the other in a commons.

"What we like about them is that you can move crowds without getting into a confrontation," McGee said. "We use the car device at sporting events, in the parking lot after the games where people start congregating and the problems start. We'll switch it on and immediately you'll see heads turn around. They become irritated from the noise, and within about five minutes, they've all gone somewhere else."

Stapleton said he settled on a tone of 17 kHz at 85 decibels, a tone his children very negatively responded to. He then ramped up the irritating sound by making it peal at four times a second. Stapleton ultimately manufactured the Mosquito for commercial and law-enforcement use worldwide under his company, Compound Security Systems. He's sold more than 4,000.

Stapleton says that at 85 decibels, the sound is equivalent to heavy traffic and would only do permanent ear damage if someone were exposed to it for eight continuous hours. The level is also the U.S. federal noise standard to which workers can be exposed without wearing protective gear.

"One-time exposure to 85 decibels intensity level will not necessarily cause hearing loss," said Colleen E. Ryan-Bane, an audiologist at Johns Hopkins. "However, prolonged, consistent exposure to 85 decibels and above will cause hearing loss."