The Toronto Star reports:

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.

Toronto police have purchased four, long-range acoustic devices (LRAD) — often referred to as sound guns or sound cannons — for the upcoming June 26-27 summit, the Star has learned.

Maybe they’re expecting some big green guy?