aaandre sends word of the use of a "sound cannon" on G20 protesters in Pittsburgh. Only a few hundred protesters took to the streets. The NY Times notes: "City officials said they believed it was the first time the sound cannon had been used publicly." The device projects a narrow beam of extremely annoying sound, at levels that can reach 151 decibels, over a distance of a mile or more. The Guardian notes, "It is feared the sounds emitted are loud enough to damage eardrums and even cause fatal aneurysms." Officials of the company that manufactures the sound cannon say that ear damage is only possible if someone manages to stand directly in front of the device for an extended period.