We’ve spent the morning trying to figure that out.
Yesterday the Prince of Petworth posted some photos of a white, box-like contraption hanging at the top of the Metro escalators at 7th and H streets NW. As PoP noted, the device looks an awful lot like the Mosquito, a controversial device that came out of South Wales just a few years ago. The Mosquito emits annoying, high-pitched sounds intended to drive off loiterers. According to Wikipedia, the frequencies are high enough that usually only people under 25 can hear it — in other words, it’s supposed to discourage teenagers from hanging around.