Yeah, that stuff is pretty scary. Two major problems with development, though: intesnity of a sound wave decreases rapidly (inverse square) as you move away from a source - but I suppose there are ways around that. That, and it's pretty trivial to reflect a sound wave, especially if the amplitude is low. IIRC, this works by directly affecting your brain, and organs, as you can't hear that low... not too sure you could actually cause organ ruputre, but probably knock someone out if the intensity is high enough, and probably mess them up psychologically. However, earhquakes also make infrasonic sound waves, and I don't recall seeing anything about any adverse effect caused by them - although it might be covered up by deaths from other causes at the site of earthquakes. Anyone know anything about this? I think its' pretty nifty.