The Mosquito - a controversial noisemaker aimed at young people loitering at Gallery Place - buzzes no more.

The device, which emits a high-pitched sound that can be heard only by youthful ears, went up a little more than a month ago outside the Chinatown entrance to the Gallery Place Metro station, the hub of one of the District's busiest retail and entertainment strips.

The Mosquito was installed after police and business owners received a rash of complaints about large groups of young people loitering along Seventh Street NW, sometimes getting into fights. But the noisemaker was silenced after a youth rights group complained of age discrimination, an allegation that the D.C. Office of Human Rights is investigating.

Dave Moss, director of development and operations at the National Youth Rights Association, said that at 28, he expected to be too old to hear anything when he stopped at the Gallery Place station on his way to a nearby synagogue. The device, according to its distributor, Moving Sound Technologies, emits a tone set at 17.5 kilohertz, the high end of the hearing range for 13- to 25-year-olds.

But there he was at 28 and there the sound was, in his ears: a headache-inducing tone that has made some teenagers, at least those who could hear it, move right along.

"It was a very high-pitched, dull but annoying series of beeps," Moss said. "I can see how it works. I would not have wanted to be there for a long period of time."

Moss and several other people from the youth organization - whose motto is "Live Free, Start Young" - filed complaints with the city.

"Our country is best when we challenge the status quo, when we say, 'I don't like that and I can do something about this,' " Moss said. "I don't think there is any place for this device in this country."

The device is sold mainly to schools, which activate the sound at night to ward off vandals, and to skateboard parks, tennis courts and playgrounds.

The decision to install it at Gallery Place came after a meeting in July, at the office of D.C. Council member Jack Evans (D-Ward 2), between District officials and business owners who were concerned about the impact of loitering and lawlessness.

In a letter to The Washington Post and the city human rights office, Transwestern, the company that manages the Gallery Place retail, office and residential complex, said the District's lack of an anti-loitering ordinance limits the ability of police to control crowds. According to the letter, Transwestern said at the July meeting that drugs and stolen merchandise were being sold at the Metro entrance at Seventh and H streets NW; the company recommended the Mosquito as a deterrent to loitering.

"The consensus of those attending the meeting," the letter said, "was to try the 'Mosquito' on a trial basis."