Extract below taken from the chapter on Acoustic Weapons
"...it consisted of a parabolic reflector, 3.2 meters in diameter, having a short tube which was the combustion chamber or sound generator, extending to the rear from the vertex of the parabola. The chamber was fed at the rear by two coaxial nozzles, the outer nozzle emitting methane, and the central nozzle oxygen. The length of the chamber was one-quarter the wavelength of the sound in air. Upon initiation, the first shock wave was reflected back from the open-end of the chamber and initiated the second explosion. The frequency was from 800 to 1500 impulses per second. The main lobe of the sound intensity pattern had a 65-degree angle of opening, and at 60 meters' distance on the axis a pressure of 1000 microbars had been measured. No physiological experiments were conducted, but it was estimated that at such a pressure it would take from 30 to 40 seconds to kill a man. At greater ranges, perhaps up to 300 meters, the effect, although not lethal, would be very painful and would probably disable a man for an appreciable length of time. Vision would be affected, and low-level exposures would cause point sources of light to appear as lines."