Police ordered protesters to disperse at the Group of 20 summit last week with a device that can beam earsplitting alarm tones and verbal instructions that the manufacturer likens to a spotlight of sound," but that legal groups called potentially dangerous. The device, called a Long Range Acoustic Device, concentrates voice commands and a car alarm-like sound in a 30- or 60-degree cone that can be heard nearly two miles away. The volume measures 140-150 decibels three feet away " louder than a jet engine. During the Pittsburgh protests, police used the device to order demonstrators to disperse and to play a high-pitched "deterrent tone" designed to drive people away. It was the first time the device was used in a riot-control situation on U.S. soil. Those who heard it said ... the "deterrent tone" as unbearable. Joel Kupferman, who was at Thursday's march as a legal observer for the National Lawyer's Guild, said he was overwhelmed by the tone and called it "overkill." "When people were moving and they still continued to use it, it was an excessive use of weaponry," Kupferman said. Witold "Vic" Walczak, legal director for the American Civil Liberties Union in Pennsylvania, said the device is a military weapon capable of producing permanent hearing loss, something he called "an invitation to an excessive-force lawsuit." Catherine Palmer, director of audiology at the University of Pittsburgh Medical Center, said 140 decibels can cause immediate hearing loss. ["Public safety"] officials said the complaints prove the device worked as designed.