Resonator

Sonic Warfare - against card board boxes!

“Anyone within 30 to 50 meters from the cannon will feel like he’s standing in front of a firing squad,” he said. “He’ll feel and hear the blast, but he won’t be hurled to the ground. He’ll be able to run away unharmed … and that’s the point of this application.”

See also:

http://armytec.net/index.php?option=com_content&view=article&id=64&Itemid=67
http://www.physorg.com/news183142646.html
http://pdtagro.com/