Using sound sensors that detect infrasound, scientists discovered quite by accident that the spinning core or vortex of a tornado produces sounds that are a few hertz below the human bandwidth of hearing. The tornado, much like an organ pipe, produces low frequencies when the vortices are large, and higher frequencies when the vortices are small. Since the infrasound waves from tornadoes can be detected for up to 100 miles away, they could help increase the warning time for tornado strikes.