The Long Range Acoustic Device, or LRAD, is a speaker system and sound energy weapon developed in the early 2000s for use by the U.S. military. It renders sound in directional focus and at extreme volumes, allowing the user to make sound audible over greater distances, and with more geographical precision, than an ordinary loudspeaker. These audio devices, colloquially known as “sound cannons,” can be used either as conventional public address speaker systems or to generate extremely loud high-frequency sounds specifically intended for the dispersal of crowds, which can also cause pain, disorientation, and injury to those exposed to them.