Posted by Joe Lorenzino on Saturday, May 10, 2003 at 10:01PM :
In Reply to: Re: Off Topic Help Needed posted by Vaughn on Saturday, May 10, 2003 at 11:55AM :
As far as the low frequency, I know that we can’t hear them, BUT we DO FEEL them. I vividly remember a synthesizer demonstration at school where the operator turned the machine down to 10 hertz, and asked if we could hear it. No, we couldn’t hear it, but the entire room breathed a collective sigh of relief the moment he switched it off. Anybody with a simple tone generator and a decent stereo could produce this same effect.
Now lets say that someone had a low frequency “emitter” near you. If you were standing at a “resonant” distance from a reflective object (like a building) the effect could have been quite noticeably increased due to the “interference” caused by the reflected wave. This would be very localized, and by moving a few feet closer to either the source, or the reflecting surface, the intensity of the wave drops to near zero.. The same sort of effect can happen when 2 different frequency waves meet, or are just slightly out of sync. This is what causes the “throb” of a multi engine plane, train, etc.
During WWII, the Germans built a "sound gun" that was capable of generating a sound / pressure wave with enough power to seriously injure or kill, but it proved to be so large and cumbersome that it was never used. It used a series of timed gas/oxygen explosions in a resonant tube, and parabolic reflectors, to create the pressure wave, kind of like a giant pipe organ pipe. Maybe someone on the internet revived the “lost” technology. Joe L.