After seeing a gray ghost near his desk, researcher Vic Tandy was worried his laboratory might be haunted. But the next day, Tandy made an interesting discovery. While preparing for a fencing match, Tandy placed his sword in a vise. He then noticed the blade was vibrating on its own. All of a sudden, everything clicked. He realized the force causing his sword to shake was the same force haunting his lab. Vic Tandy was dealing with infrasound.
Humans can hear sounds up to 20,000 Hertz, but we’re unable to detect anything lower than 20 Hz. These “silent” noises are called infrasound, and while we can’t hear them, we can feel them in the form of vibrations. Dr. Richard Wiseman says we can feel these waves, especially in our stomachs, and this can create either a positive feeling (such as awe) or a negative feeling (such as unease). In the right surroundings (see “creepy house”), this might create a sense of panic.
Infrasound can be produced by storms, wind, weather patterns, and even everyday appliances. Returning to Vic Tandy, after witnessing his wobbling sword, he learned that a new fan had been installed in his laboratory, and sure enough, it was issuing vibrations of about 19 Hz. Since our eyeballs have a resonant frequency around 20 Hz, the infrasound was vibrating Tandy’s eyeballs and creating images that weren’t really there. When Tandy turned off the fan, presto: no more ghost.
Similarly, Dr. Wiseman believes these vibrations are responsible for paranormal activity in “haunted” locations. For example, when investigating two underground sites, he discovered evidence of infrasound coming from the traffic overhead. Wiseman thinks this explains the ghostly figures and creepy footsteps in these areas, proving there’s nothing good about these vibrations.