I once heard Arthur C. Clarke valiantly attempt to come up with a way of scientifically explaining such paranormal phenomenon as ghosts and haunted houses. The best that he could do was to speculate that somehow walls are able to "record" visual images–and then somehow play them back. Consider it the even-kookier cousin to the wild theory that it might be possible to hear sounds that were unintentionally "recorded" in the grooves of ancient pots while they were being formed on the wheel–and then play them back like a vinyl LP. Now as it turns out, there might actually be a valid explanation for the weird sensations–shivers down the spine, feelings of dread–that people experience and blame on supernatural manifestations. Research presented at this week's British Association for the Advancement of Science conference in Manchester, England, suggests the extreme bass sound known as "infrasound" produces a range of bizarre effects in people. Those results come from an experiment in which Richard Lord of England's National Physical Laboratory and psychologist Richard Wiseman of the University of Hertfordshire in southern England played various pieces of music for concertgoers while secretly emitting infrasound frequencies from 21-foot long pipe. Lord and Wiseman then asked listeners to record their reactions, with a fifth of them reporting feeling of unease or sorrow during the infrasound portions of the concert.
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And what is is infrasound exactly? It's usually defined as sonic vibration that occurs fewer than 20 times a second, or 20 Hertz (a piano's bottom note C, for example, vibrates at roughly 33Hz, a frequency near the lower limit of our hearing range) and should not be confused with ultrasound, which refers to sounds above the upper limit of human hearing.
According to Infrasonic–a group Lord works with that experiments with infrasound and music–we are constantly surrounded by infrasound, much of it generated by natural phenomena such as thunderstorms, earth tremors, ocean waves and volcano eruptions. But, the site notes, humans generate plenty of inftrasound, too: "Deep below the rumble of city traffic, there is a cacophony of very-low-frequency noise from factories, lorry engines, fireworks, passing aircraft, distant quarrying and many other human sources. In 1957, the French physicist Vladimir Gavreau highlighted this overlooked noise pollution, citing it as a possible cause of city dwellers' stress." Elephants also communicate using infrasound.
This research serves as a spooky sequel of sorts to a paper Wiseman published earlier this year in the British Journal of Psychology, which theorized that spectral sightings may be just a psychological reaction to environmental factors. His team conducted experiments at locations–one in Surrey, England, the other in Edinburgh, Scotland–with ghostly reputations. Subjects visiting those areas reported significantly more "unusual phenomena" (such as a chill in the air or a strong sense of presence) in those areas than in others, even when they were unaware of the sites' spooky lore. The same locations also tended to have unusual environmental conditions, such as strongly varying magnetic fields or lighting levels.
Wiseman, a magician in his youth, published a "superstition survey" earlier this year. It found, among other things, the Scots to be the most superstitious group in the United Kingdom, followed by the English, Welsh, and Northern Irish. Also, women tended to be more superstitious than men. The most popular superstitious act: knocking on wood.
