Have you ever had a seemingly spontaneous feeling of dread, hair on the back of your neck raising, chills, nervousness, fear, and even ghost sightings? All of these are commonly thought to have to do with Halloween or the supernatural, but they also may be caused by a certain kind of sound.
Infrared sounds, or sound below 20Hz, have been linked to many of these supernatural or awed feelings. Generally these sounds are below typical human hearing, but the body sometimes still perceives the sounds in an unconscious way.
It is thought that this is caused by ingrained responses to more natural occurrences of low pitched sounds. Storms, earthquakes, bombs, some predators, etc. all emit sounds within the infrared zone of sound, and all are deeply associated with fear and panic within the animal parts of our brains. This may be why some animals that can perceive lower pitches than humans are known to run from the area of an earthquake before it actually happens.
In order to study this phenomenon, one group listened to a normal concert and the other listened to a concert with infrared sound piped in. Of this group, 22 percent felt nervous or fearful.
Another researcher that felt symptoms of a ghost sighting, even to the point of perceiving a ghostly form in the corner of his eye, set out to find what was really going on. He found that a certain fan, as well as the resonance of the room, caused an infrared sound to be emitted that was powerful enough to vibrate sheet metal when held in a vice. It is believed that this sound wave was powerful enough to resonate with the human eyeball, causing smeared vision and the perception of a ghost. Removal of the fan caused the feelings of the otherworldly and ghostly apparitions to disappear.
So this Halloween if you happened to be out and suddenly feel that there is something supernatural at hand, know that it might be due to infrared sound, or a friendly trick-or-treater.
Tandy, V. (1998, April 1). The Ghost in the Machine. Retrieved October 27, 2014, from http://www.richardwiseman.com/resources/ghost-in-machine.pdf
Infrasound linked to spooky effects. (2003, September 7). Retrieved October 27, 2014, from http://www.nbcnews.com/id/3077192/#.VFEwOfnF8b0
“Vanlig” by Jahzzar
“Brain in Blue” by SilverGryphon8
“Sound Wave” By Luis Lima89989 (Own work) [CC-BY-SA-3.0], via Wikimedia Commons