There is growing criticism of Philadelphia officials’ decision to install sonic devices called the Mosquito that constantly emit extremely loud, high-frequency noise from 10:00 p.m. to 6:00 a.m. every night designed to be audible only to persons aged 13 to 25, according to a Friday report by NPR’s Morning Edition.
The working principle behind the devices, produced by Vancouver-based Moving Sound Technologies (MST), is that older people cannot hear such high frequencies due to hearing loss from ageing and noise pollution, though that is far from universal. The Mosquito emits an awful sound in the 17.5 to 18.5 kilohertz range that is supposed to disperse potential troublemakers to at least 130 feet. It is supposedly inaudible to most people over 30; in 2005, the New York Times described an active Mosquito as like “someone had used anti-teenage spray around the entrance, the way you might spray your sofas to keep pets off,” adding those who could hear it said it is “extremely annoying”
According to a report from WPVI last month, there are now some 31 Mosquito devices in the city’s parks, with almost all of the facilities listed as playgrounds or recreation centers.
Philadelphia’s Parks and Recreation department told WPVI that the devices, which cost $5,000 to install, are brought in at the request of community members, a district council leader, and in one case the police, and are intended to dissuade vandalism and disruptive gatherings. MST president Michael Gibson told Morning Edition the devices “move, non-confrontationally, youth from an area where they should not be” and prevent “graffiti [and] loitering.”