The Thunder Generator uses mixture of liquefied petroleum, cooking gas, and air to create explosions, which in return generate shock waves capable of stunning people from 30 to 100 meters away. At that range, the weapon is absolutely harmless, making people run in panic when they feel the sonic blast hitting their bodies. However, at less than ten meters, the Thunder Generator could either cause permanent damage or kill any person.
Gizmodo: Sound Generator Could Kill Humans at Ten Meters
(Thanks Bill)