Infrasonic Symphony

The greatest sounds never heard

“Let me start off with a riddle,” says NASA scientist Allan J. Zuckerwar. In his office in Hampton, Va., he rattles off items as dissimilar as rhinoceroses, supersonic aircraft, and hurricanes. “Now, what do they have in common?” The answer, Zuckerwar explains, is that each one generates silent infrasound—long sound waves at a frequency below 20 hertz.