Infrasound
Infrasound is sound below 20Hz and the human hearing range.
It was used by the Allies in the Second World War to locate artillary and some animals such as elephants and whales use it for communication.
It has been suggested that infrasound could be responsible for ghost sightings: the low frequency sound waves could cause eyeballs to vibrate.
It was used by the Allies in the Second World War to locate artillary and some animals such as elephants and whales use it for communication.
It has been suggested that infrasound could be responsible for ghost sightings: the low frequency sound waves could cause eyeballs to vibrate.