Police Use Acoustic Warfare to Disperse Crowds

Protesters march against the G20 Summit in Pittsburgh during the G20 Summit, Friday, Sept. 25, 2009. (AP Photo/ Philip Scott Andrews)

(AP)

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. It is about two feet square and mounted on a swivel such that one person can point it where it's needed. The volume measures 140-150 decibels three feet away — louder than a jet engine — but dissipates with distance.

Robert Putnam, spokesman for the manufacturer, San Diego-based American Technology Corp., said it's "like a big spotlight of sound that you can shine on people."

"It's not a sonic cannon. It's not the death ray or anything like that," Putnam said. "It's about long-range communications being heard intelligibly."

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, according to American Technology and police.

Those who heard it said authorities' voice commands were clear and sounded as if they were coming from everywhere all at once. They described 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."