Broadway Plaza has installed a unique security device — an electronic gadget that emits a high-frequency, unpleasant sound most adults cannot hear — to discourage teenagers from loitering, Walnut Creek Patch has learned.
Shelly Dress, senior property manager for , confirmed Wednesday that one of the devices was installed in the “back corner” of the center’s parking garage, across the street from .
Dress said the device has been in place for about 18 months. It has helped to cut down on the number of teens who congregate in that part of the garage, she said. The parking structure is close to .
The device is known by various names. In Great Britain, where the gadget was first used commercially, it’s known as the “Mosquito,” a name bestowed by its inventor, Howard Stapleton. In the U.S., one brand is marketed as the SonicScreen. Dress wasn’t sure what brand was installed at Broadway Plaza.
It works by emitting a pulsing sound at a very high frequency, about 17.4 kHz, that can usually be heard only by people in their teens and early 20s. The ability to hear high frequencies declines as people age. According to the SonicScreen manufacturer, the sound is undetectable by people over age 25 or under 12 and cannot be heard by animals.
Similar technology has been used to create cellphone ring tones that teenagers can hear in, for example, a classroom, while their teachers can't.
Teenagers often describe the noise as a high-pitched buzz.
“Most customers can’t hear it,” Dress said. She added that even people young enough to hear the noise aren’t especially bothered by it if they just park and then walk away.
“But if they are loitering, it becomes annoying,” she said.
The device, which appears to be a metal box, is mounted on the ceiling of the parking structure.
Dress said only one of the devices was installed at Broadway Plaza.
“That’s the only area where we have had loitering,” she said. The device is not meant to prevent teenagers from parking in the structure, she added.
Commercially, similar devices are marketed as security tools to discourage loitering, drug use, vandalism and graffiti at businesses and parks. In Europe the Mosquito has been a source of controversy, with detractors saying it infringes on the human rights of young people.
Lt. Bryan Hill of the said the department was not aware of the device and was not consulted about its installation.