Along with the roar of a grizzly bear and a crack of lightning, the sound of a tornado is among the most terrifying natural sounds on Earth. Depending on the twister and where you’re standing, it can sound like a hiss, a buzz, a rumble, or even a freight train. It’s the auditory manifestation of trouble. But tornadoes also seem to emit low-frequency sound waves called infrasound that the human ear can’t hear.

Learn about your ad choices: dovetail.prx.org/ad-choices