Experimenting with Low Frequencies
Some of us future engineering types, in our youth, noticed that if a car was traveling at the right speed with the window(s) opened just so, the occupants would be pummeled with pulsing sound waves that caused intense confusion and extreme discomfort. In my beater I had to be doing a tad shy of 60 mph and both front windows rolled down (yes kids, "rolled" down) about 3/4 the way.
Playing around in high school shop class we created some similar pulses using some frequency generators and a pair of crappy stereo bass speakers. I remember the two speaker frequencies had to be the same but out of phase.
Even as we experienced this it was tough to localize where the effect was in the body. It could be the chest cavity, or just behind the ears. One guy said he felt it in his shoulder blades. But it was intensely uncomfortable to stand between those speakers.
Biting the hand that feeds IT
