The Power of Sound: How a Giant Subwoofer Can Help Prevent Disasters

This speaker uses "infrasound" (inaudible, sub-bass sound waves) to prevent certain accidents, at least in theory. By directing the sound waves at a mountain, the designer believes he can prevent avalanches. On an airplane, other sound waves can keep birds away from engines. Interesting idea, though you have to wonder whether the sound waves would have unintended effects on the environment.