Infrasound is sound with a frequency too low to be heard by the human ear. The study of such sound waves is sometimes referred to as infrasonics, covering sounds beneath the lowest limits of human hearing (20 hertz) down to 0.001 hertz. This frequency range is utilized by characterized by an ability to cover long distances and get around obstacles with little dissipation.
Infrasound has been known to cause feelings of awe or fear in humans. Since it is not consciously perceived, it can make people feel vaguely that paranormal events are taking place.
In 1998, computer specialist Vick Tandy from Coventry University always spent a lot of time in his laboratory. On one night, he suddenly broke into a cold sweat. He felt somebody was watching him with sinister eyes. Suddenly, a gray material form crossed the room and approached Vick. In the vague outline Vick could discern legs, arms and fog where the figure must have a head; there was a dark spot in the center of the fog which might be a mouth. The vision disappeared in the air without leaving a trace.
Soon Vick Tandy managed to discover the factors quite accidentally. Vick's hobby, fencing helped him with it. Some time after the scientist saw the "ghost" he brought his rapier to the laboratory to set it right before a forthcoming fencing tournament. Suddenly Vick felt the blade gripped in a vice started vibrating more and more as if some invisible hand touched it. Vick suddenly arrived at a conclusion that the moving of the blade was resonance oscillations caused with sound waves. He measured the sound in the laboratory and was surprised to see that the sound in the room was incredibly loud; the sound waves were inaudible, but the oscilloscope detected a large amount of noise.. That was infrasound. It took the scientist a lot of time to find out the source of the infrasound; it was emitted by a recently set ventilator in the air conditioner. As soon as the air conditioner was switched off, the blade stopped vibrating.
The same can be said for the crew of “The Flying Dutchmen”, ships that wandered around the seas without crews on board. The ships were in good repair, but there were no personnel on board. The mystery was unsolved for decades, until it became clear that infrasound was the explanation of the phenomenon. As it turned out, infrasound of seven hertz emitted by ocean waves under some definite conditions was the reason of it. But infrasound of seven hertz is terrible for people: they may go mad and throw themselves overboard
Further investigation of the phenomenon revealed that sound waves of this low frequency may appear rather frequently under natural conditions. Infrasound arises when strong gusts of wind clash with chimneys or towers. These heavy basses penetrate even through very thick walls. Such sound waves start rumbling in tunnel-shaped corridors.
Scientific studies (Infrasonic Research):
On 31 May 2003, two concerts were staged, back to back, at the Purcell Room London. Each concert featured an hour of contemporary music for piano and electronics, performed by Genia and a new film piece by Ravi Deprees, specially created for the event. At four points during the show, the audience were asked to fill out a page of a questionnaire. This was designed to measure their emotional response to the music and log any unusual experiences (such as shivers down the spine). The questionnaire and psychology experiment were designed by psychologists Ciaran O’Keefe and Professer Richard Wiseman
Just before two of these points, as the audience were absorbed in the film and music, the project team flooded the auditorium with infrasound. The infrasound was produced by a specially made generator and had a frequency of 17Hz.
The two Purcell Room concerts were identical in every aspect, except the use of infrasound. If the generator was on in one piece in the 3pm show, it was off in that piece in the 5pm show (see which pieces had infrasound below). We were careful to use the infrasound at moderate levels so it would be on the cusp of perception. The music masked the infrasound - in theory this meant the audience were never fully aware of its presence. Varying where we put the infrasound enables us to rule out the emotional effects of the other elements of the concert (the music, performance and film).
During the concert, infrasound boosted the number of strange experiences reported among the audience, even among those who were unaware of its presence. Unusual reports included a sense of coldness, anxiety and shivers down the spine.
On average, infrasound boosted the number of strange experiences by around 22%. It also increased the intensity of any feelings reported. Many unusual experiences were reported during the concerts, ranging from the emotional (e.g. ‘sense of sorrow’, ‘brief moment of anxiety’, ‘excited’) to the physiological (e.g. ‘increased heart-rate’, ‘headache’, ‘tingling in neck and shoulders’, ‘nausea’, ‘sense of coldness’). The majority of reported experiences were physiological.