I've felt my stomach getting upset by a subwoofer we used to have at the cinema (a Sensurround speaker that I have in my garage now 
) but not enough for the embarrassing, er, action. I stood right next to it when we were testing frequency sweeps.
I've heard about that effect on the eyes, DD, but I haven't had the opportunity to test it.
I had not heard anything about this effect when I built the resonator cabinet.
I had read that low frequency (sub-audible) sound pressure causes people to panic. The theory is that evolution has taught us that only large, dangerous things produce these types of sounds and we should always fear them and "run away."
I had also read sketchy accounts of how Hitler, on the advice of some of his best scientists, used this low frequency technique to drum up his audiences into a state of frenzy. I was intrigued! I wanted to play with this idea, so I built a system, using Hemholtz's theories, to create high pressure sub-audible tones. I was in my twenties and had only a smattering of education about acoustics at the time. Just getting started, so to speak. It worked quite well, though. It made VERY LOUD sub-bass noise!
It was only after I began using a sweep generator, instead of a steady tone generator, that I realized that at certain frequencies the "air" was excited to the point that it became difficult to see through. At first I was convinced that the effect was due to the building, where my dad's shop was and that the dust in the air was becoming "aligned" in some way, following the waveforms.
My theory did not hold after I thought about the wavelengths I was producing. If this was because of "dust in the air," then I would be able to step a few feet away from the sound source and the effect would change and become more or less prominent - possibly displaced to another part of the room. I should have been able to find nodes and nulls from acoustic cancellation and reinforcement. I KNEW that much.
All I could really prove at first was that I, along with all the friends who I could convince to listen to me, became very agitated during any attempts to figure out what was going on. We faught like chickens! My first idea, to try to repeat Hitler's speech frenzies, was apparently working on some level.
I had actually used the system, secretly, under the stage at a large religious recital I was working sound on, and I saw the people in the near rows going nuts. I don't believe that it was only due to the preacher's face, either. I feel like I had abruptly altered his message to many of his followers with my resonator. I used it three times with the same ("Dr. Oreo", I called him) religious recitalist, but I became afraid, at this point, that I would be discovered and it would reflect badly on my sound jobs if anyone happened to grasp what I was doing.
I just did a google but came up with the wrong "Dr. Oreo." It was a Mexican man in his late years in the seventies who I "pranked," not this woman from Pennsylvania. Maybe it was a relative or something, but Diorio is not an uncommon name in certain circles.
I had shelved the enclosure for a couple of years and pulled the drivers out of it to use elsewhere when I read about the resonance of the human eyeball/socket and began to play with the system again. That is when I was more able to understand what I was doing and created a repeatable visual disturbance in anyone willing to let me "Play With Their Emotions."
BTW, good luck on your outing!!
