" Infrasound is sound that is lower than the normal limit of human hearing, usually quantified at 20 hertz or cycles per second. Infrasound sometimes results naturally from severe weather, surf, lee waves, avalanches, earthquakes, volcanoes, waterfalls, auroras, and lightning. It’s believed that animals can detect infrasound and it is the reason they flee when severe weather, like a tsunami, is approaching. So Vic Tandy saw a ghost in his lab and attributed it to infrasound playing tricks on his mind. "

― Zak Bagans , Dark World: Into the Shadows with the Lead Investigator of The Ghost Adventures Crew