Bestbang4thebuck, garcianc2003 and all - the Wikipedia article on Gavreau (sorry for doubting his existence) has other material on infrasonics that leave little doubt what the "possibilities not revealed" are for the big military subwoofer. High-level sounds in the upper infrasonic range - just where the BMS is most powerful - seem to cause a variety of unpleasant responses in humans, ranging from "uncanny" feelings to visual hallucinations that could be taken for ghosts, to (possibly) loosening of the bowels. The link from this knowledge to crowd control through induced terror doesn't take rocket science. BMS, indeed!