infra sound
Infrasound refers to sound waves that are below the human hearing range, i.e. below 20 Hz up to wave times of several minutes.
Infrasound waves are subsonic frequencies that are inaudible to humans. They are transmitted by structure-borne sound over solid materials and are caused by large-scale power machines. Also by earth movements, earthquakes, by wind or surf. Infrasound waves can cause structures, buildings and bridges to resonate and thus lead to their destruction.