SOUTH POMFRET, Vt. - Marines arriving in Iraq this month as part of a massive troop rotation will bring with them a high-tech weapon never before used in combat - or in peacekeeping. The device is a powerful megaphone the size of a satellite dish that can deliver recorded warnings in Arabic and, on command, emit a piercing tone so excruciating to humans, its boosters say, that it causes crowds to disperse, clears buildings and repels intruders. "[For] most people, even if they plug their ears, [the device] will produce the equivalent of an instant migraine," says Woody Norris, chairman...