Very low frequency sound has a creepy effect on the brain

From: http://www.planet-science.com/text_only/outthere/planet_goth/trophy.html

Have you ever entered a room that has a weird or uncomfortable feeling about it? Are you convinced that a certain room is haunted? Ghosts might be causing these feelings but the more rational explanation is that you’re just being freaked out by low frequency sound waves.

• Vibrations
All around us objects are giving off different sounds – some you can hear and others you can’t. Sounds are a type of wave that spread out from any vibrating object. Our ears are designed to detect sounds in the range 20-20,000 Hertz (vibrations per second). Sounds below this range are vibrating too slowly for us to hear but you can actually feel them with your body and we call them infrasound. Elephants use low frequency sounds to send long distance messages to each other.

• Infrasound
Infrasonic waves can sometimes be produced by machines such as vehicles, household equipment and heating and cooling systems. It has been known for some time that these low frequency waves can cause symptoms such as nausea, headaches, fatigue, insomnia, vibration of internal organs and a feeling of oppression.

• Apparitions
Could infrasonic waves could be the explanation for certain ghostly apparitions? In 1998 Vic Tandy, a lecturer at Coventry University, discovered that the haunting of a laboratory was not caused by a ghost with a passion for science, but by a 19 Hertz infrasound wave created by an extractor fan…

A ‘spook’ had been seen in the laboratory… But it seems that that the infrasonic waves in the room may have been responsible by making people’s eyeballs vibrate, causing blurring of their vision and hallucinations at the edges of their visual field. Since exorcising the ghost in the laboratory, Vic Tandy has gone on to discover that infrasound waves were also the cause of the supposed hauntings of a 14th century cellar in Coventry.