Besides the Vortex Gun and Wind Cannon, invisible and powerful air waves were used in another devise designed by scientists at Lofer, in the form of the so-called "sound cannon." Designed by Dr. Richard Wallauschek, the cannon consisted of large parabaloid reflectors, the final version of which had a diameter over 3m. The "dishes" were connected to a chamber composed of several sub-units firing tubes. The function of these tubes was to allow an admixture of methane and oxygen into the combustion chamber, where the two gases were ignited in a cyclical, continuous explosion. The length of the firing chamber itself was exactly a quarter of the wavelength of the sound waves produced by the on-going explosions. Each explosion initiated the next by producing a reflected, high-intensity shockwave, and so creating a very high amplitude sound beam. This high and strong note of unbearable intensity was emitted at pressures in excess of 1,000 milibars about 50m away. This level of pressure is above the limits that man can endure. At such a range, half a minute of exposure would be enough to be lethal. At longer ranges (about 229m), the effect would be excruciating and a soldier would be incapacitated for some considerable time afterwards. No operational or physiological tests were ever carried out. It was suggested, however, that laboratory animals were used to prove the basic soundness of the concept. The cannon was never deployed for its intended purpose.

Photo of the Schallkanone: http://www12.reocities.com/Pentagon/2833/wunderwaffen/supergun/soundcannon/soundcannon.jpg