What he had discovered, aside from an awesome new way to torture interns, was infrasound. It's noise at a low enough frequency that you don't consciously hear it, but your ears still sense it. The process of receiving sensory input without your conscious mind understanding where it's coming from wreaks havoc with your emotions. Specifically, researchers found that sounds between 7 and 19 Hz it could induce fear, dread or panic.Infrasound linked to spooky effects
Knowing this is an article about ghosts, you can already see where this is going.
Their unusual experiences included feeling uneasy or sorrowful, getting chills down the spine or nervous feelings of revulsion or fear.Infrasound
“These results suggest that low frequency sound can cause people to have unusual experiences even though they cannot consciously detect infrasound,” said Wiseman, who presented his findings to the British Association science conference.
In 1998, Vic Tandy, experimental officer and part-time lecturer in the school of international studies and law at Coventry University, and Dr. Tony Lawrence of the psychology department wrote a paper called "Ghosts in the Machine" for the Journal of the Society for Psychical Research.(PDF) They cited infrasound as the cause of apparitions seen by staff at a so-called haunted laboratory in Warwick.Neil DeGrasse Tyson and Eugene Mirman on StarTalk, about Vic Tandy and infrasound. The Southwest Ghost Hunters Association carried out their own experiment. Vladimir Gavreau is considered the 'father of infrasound, as detailed in the article The Sonic Weapon Of Vladimir Gavreau, from The Journal of Borderland Research. Vic Tandy published again in Something In The Cellar, and his research into infrasound continued at Mary King's Ghost Fest in Edinburgh.
Several years earlier, Tandy was working late in the "haunted" Warwick laboratory when he saw a gray thing coming for him. "I felt the hairs rise on the back of my neck," he said. "It seemed to be between me and the door, so the only thing I could do was turn and face it."* But the thing disappeared. However, it reappeared in a different form the next day when Tandy was doing some work on his fencing foil. "The handle was clamped in a vice on a workbench, yet the blade started vibrating like mad," he said. He wondered why the blade vibrated in one part of room but not in another. The explanation, he discovered, was that infrasound was coming from an extractor fan. "When we finally switched it off, it was as if a huge weight was lifted," he said. "It makes me think that one of the applications of this ongoing research could be a link between infrasound and sick-building syndrome." When he measured the infrasound in the laboratory, the showing was 18.98 hertz--the exact frequency at which a human eyeball starts resonating. The sound waves made his eyeballs resonate and produced an optical illusion: He saw a figure that didn't exist.*
Experimental studies have been reported where humans or various species of animals (rats, mice, guinea pigs, chinchillas) have been exposed to infrasound in the laboratory. Most of the studies identified involved exposures at 90 dB and higher and ranged from minutes to several months. Of the many animal studies identified, there were none involving long-term (six months or greater) exposure and few that employed modern toxicology testing protocols and pathological assessments. The most common endpoints studied were behavioral, sensory, or simple physiological (e.g. blood pressure) changes. Some studies focusing on biochemical, cellular, or morphological changes in organs and tissues were identified. There were few studies evaluating reproductive function, developmental effects, and immunological effects, and no studies that evaluated carcinogenic effects. Most studies reported some effects attributed to infrasound exposure, though many studies also reported no observable effects. Among the more consistent findings in humans were changes in blood pressure, respiratory rate, and balance. These effects occurred after exposures to infrasound at levels generally above 110 dB.Acoustic Weapons
Low-Intensity Effects of Low-Frequency SoundSpeaking of acoustic weapons: What Sane Person Would Listen to 24 Hours Of Throbbing Gristle?
Effects of low levels of low-frequency sound are not relevant for weapons; they are mentioned here only for the sake of completeness.Annoyance by infrasound has occurred at widely differing levels, from 120 dB inside motor vehicles to below 60 dB in neighborhoods affected by industry sources.
In a systematic study annoyance seemed related to the loudness sensation, however.
In some cases, indirectly- produced audible rattling noise may be a main reason for annoyance.
Stress hormones in-creased in rats after infrasound exposure to 100-120 dB; in humans, this occurred only when subjects had not slept.
Sleep was influenced somewhat by 80-100 dB low-frequency noise.
Some people seem to be more sensitive to low-frequency sound (and/or rattling noises) than others, which may lead to stronger physiological responses.
Air is a very inefficient medium for transferring low frequency vibration from a transducer to the human body.[7] Mechanical connection of the vibration source to the human body, however, provides a potentially dangerous combination. The U.S. space program, worried about the harmful effects of rocket flight on astronauts, ordered vibration tests that used cockpit seats mounted on vibration tables to transfer "brown note" and other frequencies directly to the human subjects. Very high power levels of 160 dB were achieved at frequencies of 2–3 Hz. Test frequencies ranged from 0.5 Hz to 40 Hz. Test subjects suffered motor ataxia, nausea, visual disturbance, degraded task performance and difficulties in communication. These tests are assumed by researchers to be the nucleus of the current urban myth.[8]To be sure, that last citation appears broken. The talk page mentions Mythbusters.
If I were nasty rich, I'd attempt to put together a PA rig that was My Bloody Valentine levels of sound coupled with infra/ultra sonic frequencies.You don't need to be nasty rich. Just design the system on paper, and work up some renderings in various shades of olive drab. Then contact the department of defense and various local police departments that have recently purchased SWAT tanks. Wait for the contracts to roll in.
nebulawindphone: Going from "different sources claim values from 12Hz through 70Hz; we found one source that mentions 18Hz" to "the value is precisely 18.98Hz" makes it look like they're more interested in truthiness than in actual truth.Thank you, nwp. That's bullshitty reporting. Not even the spectral response range of human vision displays that much precision - even though that's mostly based on the bulk properties of the lens and vitreous.
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