Toronto Police Get 'Sound Cannons' for G20  http://axisoflogic.com/artman/publish/Article_60032.shtml

Riotous protesters marching at the G20 summit next month may be greeted with ear-splitting "sound cannons," the latest Toronto police tool for quelling unruly crowds.Of Toronto's newly-acquired LRADs, three are handheld devices that can broadcast noise heard from 600 metres away. Their volume can reach 135 decibels, which surpasses the pain threshold of 110 to 120.

The fourth device is a larger model that can be mounted on vehicles or marine vessels and can generate noise reaching 143 decibels, audible from as far as 1500 metres.Wired.com has a series of articles on the use and danger of LRAD. To compare, a normal conversation measures at about 60 decibels. The U.S. National Institute on Deafness says sustained noise above 85 decibels can cause permanent hearing damage.