This seems like a harmless tube. In fact, it was harmless: Jewish farmers used the first version to scare birds from crop fields. Then, somebody converted it into a crowd dispersion mechanism. And then, they discovered it could kill.
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
Full story: Sound Generator Could Kill Humans at Ten Meters – Gizmodo