A point I've made here more than once is that my doubting many claims of the paranormal isn't because I think it's necessarily impossible, but because our sensory-interpretive systems are so fundamentally flawed.
I mean, they work well enough, for most of us most of the time. But not only do we have the capacity to miss a great deal of what's going on around us -- as the famous experiment in which a great many test subjects failed to notice a guy in a gorilla suit showed -- what we do sense is all too easy to misinterpret or remember incorrectly. This is why if someone comes to me with a claim of some supernatural occurrence or another, I'm going to ask for some kind of hard, scientifically-admissible evidence. To quote astrophysicist Neil deGrasse Tyson, "I need more than 'you saw it.'" Neither he nor I are accusing anyone of lying or perpetrating a hoax; the problem is that eyewitness testimony is all bad, even if you mean well and are trying your hardest to be honest.
To throw another monkey wrench into the situation, consider the recent paper by psychologist Rodney Schmaltz of MacEwan University. Schmaltz became interested in the possible role of subsonic vibrations in claims of haunting; there was a case in England where a medical research building was claimed by several workers to be haunted, in one case by a "gray form that materialized, floated across the room, and vanished." More than one person saw the apparition, and several described a sensation of chill, as if they were being watched.
The culprit turned out not to be a ghost, but a furnace fan that had set up a subsonic standing wave in the basement. The frequency of the wave was around twelve Hertz -- so below the range humans can hear -- but created resonant vibrations in our eyes and ears that could be sensed by the brain. The result: eerie hallucinations, altered perception, and feelings of unease.
What Schmaltz did was try to see if there was a way to measure the human response to infrasound, by setting up test subjects to listen to recordings of music through headphones. Half the test subjects listened to calm instrumental music, and the other half eerie recordings that could have been the soundtracks of horror movies. What the subjects didn't know, though, was that half of each of the audio tracks had been altered to include infrasound.
The results were incontrovertible. The subjects exposed to infrasound weren't aware of it consciously, but responded to it regardless. Also, it didn't matter what the audible component was. If they were exposed to infrasound, they reported feeling unsettled and unhappy, and -- most strikingly -- a saliva test showed elevated levels of the stress hormone cortisol.
“Whether they were listening to calming instrumental music or something more unsettling, the infrasound shifted their mood and their stress response in a negative direction,” Schmaltz said. “In plain terms, you cannot hear infrasound, but your body and your mood appear to respond to it anyway, and the response tends to be unpleasant.”
