Frequencies of sound and average range of hearing
In physiology, sound is produced when an object’s vibrations move through a medium until they enter the human eardrum. In physics, sound is produced in the form of a pressure wave. When an object vibrates, it causes the surrounding air molecules to vibrate, initiating a chain reaction of sound wave vibrations throughout the medium.
Infrasound - sound waves with a frequency below the lower limit of audibility (20 Hz)
"Animal communication: whales, elephants, hippopotamuses, rhinoceroses, giraffes, okapis, peacocks, and alligators are known to use infrasound to communicate over distances—up to hundreds of miles in the case of whales."
"One study has suggested that infrasound may cause feelings of awe or fear in humans. It has also been suggested that since it is not consciously perceived, it may make people feel vaguely that odd or supernatural events are taking place."
- Infrasound, human health, and adaptation: an integrative overview of recondite hazards in a complex environment - Research by Michael A. Persinger
- The psychoacoustic effect of infrasonic, sonic and ultrasonic frequencies within non-lethal military warfare techniques - Research by Littlefield
- Infrasonic Vibrations in Humans - Research by George Rajna