Infrasound is sound with frequencies below the hearing range, generally below 20 Hz. Sounds in this range generally can’t be heard by humans, but they can reportedly be felt. Symptoms associated with infrasound include anxiety, fear, chills, sadness, a general feeling of oppression. These symptoms are suspiciously close to what people report experiencing in “haunted” places, so infrasound has been suggested as a rational explanation of hauntings. One paper (pdf) describes the case of an allegedly haunted laboratory, which turned out to be caused by infrasound of a frequency around 19 Hz that was emitted from a fan. Since the sound couldn’t be heard, it was discovered by pure luck: a researcher observed a fencing blade vibrating mysteriously and guessed that it must resonate with some sort of sound. The paper also suggests that 18 Hz is around the resonance frequency of the human eye itself, which may cause vibrations that lead to visual hallucinations. (I’d like to point out that this paper was published in Journal of the Society for Psychical Research, though. That name doesn’t exactly inspire confidence, even if the paper itself doesn’t raise any immediate warning flags.) Here’s another experiment done with music laced with infrasound, which found that 22 percent of people reported unusual experienced when listening to the infrasound-laced musical pieces, despite not knowing beforehand which pieces would include infrasound.
dailymeh posted this on January 4, 2011
