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Haunted Houses Explained: Infrasound
anagama writes "For anyone who cringes whenever accosted by topics such as psychics, haunted houses, or any sort of new age drivel; for anyone who thinks James Randi is cool or has an active subscription to the Skeptical Inquirer - you're gonna love this story about infrasound. Here's a quote: "British scientists have shown in a controlled experiment that the extreme bass sound known as infrasound produces a range of bizarre effects in people including anxiety, extreme sorrow and chills -- supporting popular suggestions of a link between infrasound and strange sensations. ... Some scientists have suggested that this level of sound may be present at some allegedly haunted sites and so cause people to have odd sensations that they attribute to a ghost -- our findings support these ideas.""
Does infrasound include the "brown note", by chance? If so, then I think that they might be on to something. I'm always shitting myself...
Life is the leading cause of death in America.
There have been news articles about infrasound and ELF sound experiments since the Cold War began. Both the US and Soviet scientists experimented extensivel y with infrasound as a weapon, and found that it was effective against troops, except for that one annoying minor problem - it affected both sides equally.
. htm
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The BBC story on the subject also attributes religious feelings in churches to the sound produced by the infrasound generated by the largest organ pipes in many churches and cathedrals.
++ Say to Elrond "Hello.".
Elrond says "No.". Elrond gives you some lunch.
Or......infrasound is how the ghosts are trying to communicate with us! All we have to do is record it and then speed up the tape! Maybe play it backwards too? You'd probably hear "Iiiii...am the ghost of Caldera.....bring me $699 or I shall not find eternal peeeaaaaace....."
...
...had this in 1964. See The Three Investigators #1: The Secret Of Terror Castle (by Robert Arthur 1964).
----- On the requirements it said: Windows 98 or better - so I installed Linux
I remember reading The Mystery of the Green Ghost (Robert Arthur, part of the Three Investigators Series) back in 4th grade (1980ish). It's originally published back in 1965, and one of the "techniques" used by the perpetrators to scare people off was using extremely low notes on a pipe organ, too low for them to hear as sound.
Putting the sig back into +1, Insightful since 1995!
"Infrasound is also produced by storms, seasonal winds and weather patterns and some types of earthquakes. Animals such as elephants also use infrasound to communicate over long distances or as weapons to repel foes."
So now we just have to explain how the elephants got into the haunted houses. Or how it is we don't see ghosts every time there's a thundershower.
Seriously, trying to come up with a physical explaination of ghost stories that doesn't include the mind of the person is dumb. The range of reported phenomina is so wide as to be clearly "made up".
(sigh) Oh Great - Just when I thought I had my Home Theater set up correctly, they invent Even Deeper Bass.
I guess I'll need to upgrade if I ever want to truly enjoy such movies as this Scary Movie
Visit CryptoGnome in his home.
A man willing to test his own beliefs! My goodness, what more do we want?!!?!
...tizzyd
Seriously, they don't mention what frequencies were used (can someone extrapolate from the pipe length), but getting transducers to work so low isn't easy and you would need a DC coupled amp. Bass speakers theoretically go down to 20Hz but the performance falls off.
See my journal, I write things there
... the real explanation for ghosts is that it was old Mr McCavity, the janitor. He knew about the abandoned gold mine under the house and used the ghost disguse to try to scare away the house's rightful owners. And he would have got away with it too, if it wasn't for those meddling kids.
Poor research methodologies produce ambiguous results: Film at 11
First, the ambiguous results: 22% reported feeling odd when the infrasound was playing. Howabout when it wasn't playing? 78% also didn't notice ANYTHING. This doesn't really demonstrate anything. Can anyone reliably determine, in a double-blind study, when the infrasound is playing? That would be interesting.
Now, the poor research methodologies: This wasn't a double-blind study. Heck, they crammed all these people TOGETHER in a concert hall. Can you IMAGINE all the "Hey, do you feel funny? I feel funny!" discussion polluting the results? If this had been a one-at-a-time, double-blind study then I suppose the results might actually be meaningfull.
Also, strange sensations like Deja Vu or Premonition I don't think can be explained through this study.
Deja Vu can be experienced by any person whose brain is properly stimulated. I worked as a Sleep Disorders Technician/EEG Technician at a hospital to finance my college education. Part of the on-the-job training was viewing videos and suggested reading by physicians and department managers. I recall seeing one video where a patient undergoing a medical study (from the 1960s) had a portion of the skull removed and the surface of the brain exposed. Doctors placed an array of electrodes on the cerebral cortex and stimulated the brain with a few microvolts of electricity. The patient, being conscious of course, said he had feelings of deja vu. On a related note, even the "tunnel experience" many people claim to see who have had near death experiences can also be stimulated without having the *real* near death experience.
Citing a strange experience, I very reluctantly went to a reknowned psychic with a close friend who said was known for helping police solve murder crimes. Being a scientist, I rejected the session as utter hogwash, but for the life of me, I cannot explain how most of everything the psychic woman told me has come true. Even the authors of the "The Mind's I", Douglas R. Hofstadter and Daniel C. Dennett have noted scientific studies that suggest some psychic phenomena cannot be explained by statistical chance alone. Perhaps these psychics are somehow able to extrapolate what clients might do in the future based on some electromagnetic signature or pattern in the brain. The reason I mention this is that part of my training as an EEG technician involved doing brain death determination studies. The test is performed using an Electroencephalographic recording instrument with the sensitivity set to the most sensitive setting. During that training, my mentor shouted in the room "nobody move", and I said "like this [waving my left arm]". My mentor then made a note in the patient log "technician waving arm" because my waving arm with an electromagnetic field was recorded in the dead patient's drain death determination EEG test. The EEG waves showing no brainwave activity from the patient, slowly swayed (very low frequency) in a manner associated with the movement of my arm. Perhaps these psychics are able to pick up on this electromagnetic field and obtain useful data from it. I know this is pure speculation without evidence, but when confronted with these phenomena, one can only guess as to a possible explaination based on current scientific principles.
Anyone who has ever witnessed a show by a heavy dub sound system (e.g. Jah Shaka) can tell you about the effects long and heavy bass signals can have on a person. Anything from dizzieness, nausea
and heavy headaches comes along. No wonder people see ghosts under the influence of ultrasound
fx! kicking and screaming
I don't know where you're coming from with this talk about a "DC coupled amp" but bass speakers go all the way down to DC (0Hz). There's certainly no practical or theoretical problems reproducing sub-20Hz signals from a bass speaker. Even your tiny 6" mid-range drivers can (and do) reproduce 1Hz signals. You just can't hear it because so little air is being moved.
The actual problem is that the lower the frequency, the more air you need to move in order to hear it. The amount of air a driver can move is partially determined by the Vd figure (volume of air moved). This is simply Sd (surface area of cone) multiplied by Xmax (cone excursion). The 1Hz signal out of your 6" drivers is so quiet that you can't hear it, but it's there. Not enough air is being moved for your ears (which are heavily tuned to 2-4kHz) to detect.
So the trick is to make the excursion large, the surface area large, thereby getting a large value for Vd. Of course, you now need a lot of power to move that much air around. That's why subwoofers have 18" cones with 1/2" excursions driven by 400W amplifiers. Grunt. Grunt. Grunt.
Of course, super-low frequency generators don't bother with all this nonsense. They just use huge pistons behind a suitably long tube. Much easier to move the required amount of air.
Scientists - 1,000,001
I can't prove something doesn't exist, but you should be able to prove something does exist.
My beliefs do not require that you agree with them.
Remember all those blue, brown, beige boxes that used to float around the net? When I was a kid myself and a friend teamed up to build the pandora's box we found on the net. It was a hacker tool to annoy people. Not that we needed much help though.
IIRC it consisted of a variable capacitator, 555 timer, and a directional speaker. What you would do was tune the device until it was just the tiniest bit past the perceptible human sound range. Then you would walk around and point it at people and see how stressed you could make them. It worked pretty good. People would get irritated very easily without knowing precisely why. Those who were very susceptible would start to sweat. It clearly induced stress.
Seems like it might be useful for haunted houses too...
A previous student had found a old organ that a church was throwing out. He had collected the assorted bits, repaired it, and put it in the back of the RPI playhouse. I had taken over maintenance of the organ. The job came with the right to tell others that you had the largest organ on campus.
As a side note, a succession of VERY talented people treated the RPI playhouse as their own personal stereo system. What appeared onstage may not have been great, but we could pump fabulous sound into that room.
One day we were running some new lines in order be able to patch the organ into our mixing board. We decided to try a test to see how hard we could drive the system. Our subwoofers were a pair of EV 20 inch speakers. Each was driven from its own Crown DC300 amplifier, located next to the speaker for minimum cable losses. The DC300s were crossed over so that both channels drove the same speaker, which has the effect of quadrupling the power output.
I played the lowest note on the foot peddles. It was around 20 Hz. We brought the power up to max and it was pretty impressive. Then I added in the second lowest note. That set up an approx. 2.5 Hz beat frequency. The curtains were up, exposing the cinder block wall behind the stage. Due to the insistance of some architects, the house was plaster, with no sound dampening. The beat frequency corresponded exactly with the length of the space, plaster wall at back of house to the cinder block wall behind the stage. At this point the house was quite uncomfortable.
We stopped the experiment, rigged the organ so that the two lowest notes would play continuously, then retired to the glass enclosed sound booth. We added an extra pre-amplifier to boost the signal a little more. Then we drove the systam as hard as we could. The technical director at the playhouse was in a classroom half a mile away. He later reported that he felt the vibration and said to himself, "What are those guys up to now." After running this for about 5 minutes we called the geology department. The seismograph did indeed capture our experiment from several miles away.
Being a scientist, I rejected the session as utter hogwash, but for the life of me, I cannot explain how most of everything the psychic woman told me has come true
Perhaps. But the truth is that you were made aware of her predictions as they were made, and therefore cannot draw any conclusions as to the validity of said predictions. A somewhat more reasonable (but hardly scientifically or statistically valid) test would be if she had taken her "reading" of you and written the predictions down on paper for you to read later, after they had come true (or didn't.) But most poeple won't pay for that: they want to know right now whether they are going to be successful, die of a blood clot, or marry the man/woman of their dreams.
And I will bet dollars to doughnuts that if you had made a recording of the event, and played it back later, you would have found that she was substantially sharper than you thought, and reeled you in like a fish. There may be true psychics out there (unlikely though that may be) but most of them are just very, very good at social engineering. The fact that you walked away believing that she had made valid predictions about you, or even if she was ultimately proven correct, says absolutely nothing about whether some paranormal or heretofore undiscovered neurological activity was involved. Unfortunately, none of the serious research that I've been able to find on the subject (and there appears to have been some) has ever shown that these powers exist. Proponents will say, of course, that such powers simply do not work in a laboratory setting. The simple way around that would be to interview and track several thousand customers of/visitors to so-called psychics and see whether any patterns appear in the recorded statistics. Recording the actual reading would be a good idea as well, so that any verbal con-artistry can be weeded out of the numbers, but I doubt that many psychics would submit to that.
Furthermore, I would want to see a name-brand university behind such a study, with some big name study-designers and statisticians behind it, before I would accept the results as having any validity. I would want some people running the show who have something to lose by performing bad science. There have been way too many "fringe science" studies done with the express purpose of proving the existence of paranormal phenomena (which is about as unscientific as one can get), rather than trying to find out what, if anything, is actually going on..
Amazing how few people grasp the tremendous utility and value of the scientific method, or even what it actually is, rather than perceiving it as a fly in the ointment of their personal belief systems. Oh well. No accounting for taste.
The higher the technology, the sharper that two-edged sword.
There is a really well done french film, "Irreversible" by Gaspard Noe that includes infrasound during one of the more unsettling scenes. I commend Noe for using such a genious technique in this film, since it really expresses the gravity of such a significant scene.
::Bleaked::
If you are even in the mood for a quality film, I highly recommend this film.
You need a DC coupled amplifier, otherwise the series capacitors found on one or both ends of an AC coupled amplifier tends to mess things up. You also need to couple this energy into the air.
..... Germanium was harder to make in N-type flavour, so germanium trannies were mainly PNP. Even when silicon took over from germanium, output stages typically were NPN-NPN. Complementary symmetric output stages - at least ones that work properly and don't give lots of even harmonic distortion - are a much later development} more cheaply than a circuit with one or more transistors ..... but that was a looooong time ago.
..... you need to make sure that the air moving away from the cone as it travels forward, doesn't simply travel around to the back of the speaker. If the cone moves slowly then this is more likely. Ideally you want to place the speaker in a heavy, sealed box. An exponential horn on the front might help too - it's the most efficient pattern for coupling a pressure wave into air. You can also use a tuned port to catch reflected sound from the rear of the cone, invert its phase by 1/2 wavelength, and then when the cone pushes at the front, the tuned port also pushes so you get reinforcement rather than cancellation.
Some stage amps are already DC coupled, others can be modded to DC couple them. Thanks to inherent close thermal matching, DC coupled amps built as ICs really do work. Think TDA2030 and bigger cousins - basically just an op-amp with a slew rate good enough for audio. Valve amps, however, almost invariably rely on transformer coupling somewhere and therefore are AC coupled. Same goes for older tranny amps where a transformer could provide the necessary phase-splitting for driving a push-pull output stage {nb, in those days they were invariably PNP-PNP
My old employer used a modified 1kW stage amp, a signal generator and a box of tricks I built with some op-amps and resistors, to apply weirdy DC+AC / DC+rectified AC waveforms to automotive kit they were testing for operation with a noisy supply. {a vehicle alternator gives out unsmoothed rectified AC; the battery acts like a massive smoothing capacitor but sometimes the lead inductance is too much for this to happen, and what if the battery becomes disconnected after the engine has started?}
As for the problem of getting air to move
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I'm a bass fanatic and infrasound has sort of been a hobby of mine for the past several years. Detecting infrasound (frequencies less than 20 Hz) is easy if you have the right equipment and it can be very fascinating, educational, and fun.
Capturing and monitoring infrasound is easy with a PC, low end sound card, and a cheap microphone. The key is having a low enough sample rate and a spectrum analysis program that is designed for monitoring long term events. I am the author of a Linux signal analysis program called baudline. It has many features that make it ideal for infrasound monitoring. For those of you who are interested in this sort of thing I would recommend checking out the image entitled -session basso on the Screenshots page, also many of Mystery Signals contain some interesting bass phenomena.
For baudline infrasound monitoring, some good starting command line parameters would be:
baudline -memory 50 -samplerate 8000 -decimateby 16 -overlap 50
This will capture about 5 hours of data at a 500 samples/second rate which is good for frequencies up to 250 Hz. Increasing the -memory buffers to 230 MB, the decimation ratio to 64, and the -overlap to 100% will have a Nyquist frequency of 62.5 Hz and capture almost a weeks worth of data!