Haunted Houses Explained: Infrasound 558
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 this include? (Score:5, Funny)
yeah (Score:2, Interesting)
Yet, on slashdot, this is breaking news.
Re:yeah (Score:3, Interesting)
60db infrasound at around 6.9-7.1 Hz is capable of driving a human insane or even killing him within a few minutes.
Imagine someone unleashing this on a crowd in peak hour.
Reference? (Score:2)
I find this hard to believe... do you have a reference or link?
Re:yeah (Score:3, Informative)
I think you seriously overestimate the potential for damage that this represents. It's mostly just annoying, not fatal. I'd think the pressure levels that are fatal are ones that cause physical damage, like the ones caused by an explosion.
Re:yeah (Score:2, Interesting)
Second, back in the day, an old Borland C++ compiler had as an example of sound, a short program with a rather interesting comme
Re:yeah (Score:3, Funny)
So what you're saying is, there is an HTML sound tag always playing infrasound in the background on /.?
Not really news... (Score:5, Informative)
http://www.borderlands.com/archives/arch/gavreaus
Re:Not really news... (Score:4, Informative)
Re:Not really news... (Score:5, Funny)
Ah HA! That's how we got Blair to say the same drivel that Bush was spouting about Iraq's WMD...
Re:Not really news... (Score:3, Funny)
Re:Not really news... (Score:4, Interesting)
Re:Not really news... (Score:2)
Re:Not really news... (Score:5, Funny)
Reminds me of the Monty Python funniest joke ever sketch where the English had to translate the joke into German one word by different researchers none of them would accidentally die.
Could someone please translate this post into English?
Re:Not really news... (Score:5, Informative)
I've also swept large sound systems for resonances from 5 hz to 20 Khz. Some large rooms resonate in the 3-7 hz range. By the article, I should be dead running between 20-500 watts between 5-25 hz while finding & fixing the light fixtures that rattle. It is true it is hard to hear frequencies below 10 Hz and they are felt at high power, but you sure can hear a chandileer rattle clear cross the room.
Re:Not really news... (Score:3, Informative)
Re:Not really news... (Score:3, Informative)
BBC has a more religious spin on the story (Score:5, Informative)
Re:BBC has a more religious spin on the story (Score:5, Insightful)
Re:BBC has a more religious spin on the story (Score:5, Interesting)
Of course, not all religious experiences are due to any of the automatic factors, but they could help significantly with getting a whole group of people to have religious feelings together. (There has, in fact, been a study of this using LSD, and it worked well). There's actually a lot of fascinating research on the subject, with very interesting philosophical implications.
Re:BBC has a more religious spin on the story (Score:5, Insightful)
The ancient mystics would have used Occam's razor to conclude the simplest explanation: some ambiguous external force. In other words, in ancient culture, Occam's razor would really have meant we were invoking spirits, because we can use "spirits" as an extremely simple mystical explanation for everyday phenomena.
In our modern skepticism, the "obvious" conclusion is, interestingly, different from the "obvious" conclusion another culture might draw.
Re:BBC has a more religious spin on the story (Score:5, Interesting)
How far below human hearing range are these infrasound notes anyway?
Plenty of psychos build pipe organs whose fundamental pitch are too low to be heard.
Pipe organ pitches are notated in terms of the length of an open flue pipe that it would take to create a pitch. An 8' long pipe plays a "C", two octaves below middle C. A 16' pipe sounds three octaves below middle C. A 32' pipe sounds four octaves below. The note E on a 32' rank is about 21 Hz. So C, Db, D, Eb are all below what you can hear.
Many large organs come with these 32' pitches. Why? It adds an incredible dimension of power to the sound when you play the full organ. You feel the music, not just hear it. It adds to the visceral experience of hearing the music. The fact that you can't hear it actually is part of the point!
Also, to drastically over simplify, there are two kinds of pipes. Flue and Reed. Flue pipes play like a flute-- just the vibration of the air creates the pitch. Reed pipes use the beating of a reed to produce the sound. If you ever heard a 32' reed like a Bombarde play, it definitely makes an audible sound. All the overtones of the reed slowly banging away. Then you have that fundamental 32' pitch shaking the floor. Really neat stuff, actually.
A very small number of instruments in the world have a 64' pitch. The Washington National Cathedral has one. The Atlantic City Convention Hall has another. http://www.acchos.org/ for more info on that one.
--Thad
Aha! (Score:5, Funny)
Re:Aha! (Score:2)
Re:Aha! (Score:3, Funny)
Wife: 'I gave him a dollar!'
'She gave him a dollar!'
Wife: 'I thought if I gave him a dollar he would go away.'
'Well of course he ain't gunna go away if you give him a dollar!
Re:Aha! (Score:2)
Re:Aha! (Score:2)
ghost (Score:2, Funny)
The Three Investigators... (Score:5, Informative)
Long known/speculated (Score:5, Informative)
I remember reading The Mystery of the Green Ghost [barnesandnoble.com] (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.
Yeah, right... (Score:5, Insightful)
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".
Re:Yeah, right... (Score:5, Funny)
Even Lower sub-sonics (Score:5, Funny)
I guess I'll need to upgrade if I ever want to truly enjoy such movies as this Scary Movie [imdb.com]
The Three Investigators knew this.... (Score:2, Redundant)
Of course, being
Re:The Three Investigators knew this.... (Score:3, Interesting)
Damn! You beat me to this. Reading the article, it isnt obvious to me as to what exactly is "new" about this research. Perhaps the "facts" quoted by Mr. Hitchcock in the "Three Investigator" books werent really facts after all, but speculations / common knowledge among film industry technicians, and this is really the first time someone has conducted a scientific study on this matter. I remember reading these books in the 1980 - 84 range, and at that time, the books were a few years old already, so this is
A sidenote on the Three Investigators. (Score:2)
I bought a few for my son, and it turns out that Alfred Hitchcock has been exorcised from these books (a license expired for the name perhaps?). He's been replaced by a generic famous film producer.
Not that it matters: my kids have no idea who Alfred Hitchcock is anyway.
Ah well.
Re:The Three Investigators knew this.... (Score:2)
Man... now I'm all nostalgic and stuff. Must...read...book...again..
That explains everything? (Score:3, Interesting)
Whatever..
Re:That explains everything? (Score:3, Insightful)
Re:That explains everything? (Score:3, Insightful)
And how does that stack against the percentage experiencing paranormal phenomena?
Re:That explains everything? (Score:4, Insightful)
Again, whatever...
Re:That explains everything? (Score:3, Funny)
Exactly! Like that one inventor back in the 1400's who invented that one clock with a piece of glass with a starmap in it that can only be seen at one place at one time ever. He even invented computers and paper-eating solutions that activate when someone opens a briefcase and everything... Oh wait, that was in Alias. Nevermind...
If you are keeping score... (Score:5, Insightful)
Scientists - 1,000,001
I can't prove something doesn't exist, but you should be able to prove something does exist.
Re:If you are keeping score... (Score:3, Interesting)
Yes there are. For instance the "giant squid" was long thought to be a myth, but they have been found in the past couple of years. There are studies that suggest prayer and meditation have positive effects. The Will O' the Wisp may have been swamp gas. etc.
But the skeptics tend dismiss any evidence for paranormal activity. Blurry UFO photo? Must be a hoax because the photographer blurred the picture to c
Re:That explains everything? (Score:3, Funny)
This explains Haunted Houses! (Score:2, Funny)
Clever ghosts.
Interesting (Score:3, Interesting)
However, there are some reports I have heard that may not be encompassed in this, unless the feelings infrasound induces also result in visions. I have heard stories of objects moving, seeing ghosts and such, and other less intangible occurances.
Of course, I've never personally witnessed any of these, so I have little to go on
Re:Interesting (Score:2, Funny)
Thank you, Mr. Spock.
Re:Interesting (Score:3, Informative)
Randi published a short story (second section on the page) [randi.org] about a scientist and his haunted lab experience involving infra-sound, but it's merely an anecdote, unlike the study.
Heinlein used this in his book Sixth Column (Score:3, Informative)
Cellphone signals cause road rage (Score:3, Interesting)
That said, I think it be contradictory to this study because it seems like to me that ghost sightings and the paranormal are not as common as they were in the 80's - to me things like this are only a fad - after movies/books like Poltergeist and Amityville Horror.
Also, strange sensations like Deja Vu or Premonition I don't think can be explained through this study.
Re:Cellphone signals cause road rage (Score:5, Interesting)
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.
Re:Cellphone signals cause road rage (Score:5, Interesting)
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.
Re:Cellphone signals cause road rage (Score:3, Insightful)
No, quantum mechanics rule the universe that we live in. We rule our lives. And I might add that how widely-believed something is has absolutely nothing to do with how factual it is.
Randi should be president! (Score:4, Interesting)
A man willing to test his own beliefs! My goodness, what more do we want?!!?!
Feeling lonely today... (Score:3, Funny)
From the article:
"[...] It's wonderful to be able to examine the evidence," said Sarah Angliss, a composer and engineer who worked on the project.
Hmmm. Let me get this straight:
I think I am in love... Will you marry me, Sarah? I just hope my wife is not reading this...
Re:Feeling lonely today... (Score:3, Informative)
Music experiment (Score:3, Funny)
The audience did not know which pieces included infrasound but 22 percent reported more unusual experiences when it was present in the music.
Their unusual experiences included feeling uneasy or sorrowful, getting chills down the spine or nervous feelings of revulsion or fear.
Of perhaps it was their unfortunate decision to place the infrasound in the Marilyn Manson and Nine Inch Nails songs vs the Kylie Minogue and TATU songs (or is the the other way around?).
James Earl Jones (Score:3, Funny)
Re:James Earl Jones (Score:3, Funny)
Yes. It also explains the feelings of fear and dread that people experience when they hear the phrase "This...is CNN". ;-)
Absolute rubbish. As everyone knows ... (Score:5, Funny)
Sensurround? "The Moon is a Harsh Mistress," 1966? (Score:3, Informative)
I don't have it at hand, but IIRC in Heinlein's 1966 novel, "The Moon is a Harsh Mistress," the central computer, "Adam Selene," uses his control over HVAC systems to generate fear-incuding subsonics at a critical point in the story?
Fundamentalist materialism (Score:3, Interesting)
This sort of closed-mindedness led to 'experts' being sure it was safe to turn cows into cannibals by mixing dead cow-parts into their feed, because 'obviously' no disease could possibly spread via proteins (ha!). If those experts had respected the fuzzy-headed tree-huggers who protested that cannibalism was unnatural, how many lives would have been saved?
The same cynical BS is responsible for hundreds of thousands of birth defects as depleted uranium and other poisons are poured into the environment-- let the cynics devote their lives to caring for crippled children.
Robert Anton Wilson calls it 'fundamentalist materialism' (in his book "The New Inquisition": Amazon [amazon.com]) because its advocates make exactly the same logical errors they claim to attack. [more ranting] [robotwisdom.com]
Re:Fundamentalist materialism (Score:3, Insightful)
Attempting to find parsimonious answers to various questions is not a wholesale dismissal of anything. Consider that it may be you who are close-minded, unwilling to accept the possibility that what you want to believe may not be the truth.
This sort of closed-mindedness led to 'ex
Re:Fundamentalist materialism (Score:3, Informative)
Or as I have often put it, science is a religion. It attempts to explain our world and justify our actions based on that explanation. It's not pure empirical observation and recording, if it ever was (remember that most of the first true scientists in the Western world were monks)
I think Hippocrates and Aristotle would be quite astounded to hear you calling them monks.
Read some Popper and then get back to us. The limitations of individual studies cannot be generalized to the statement that "science is a
Re:Fundamentalist materialism (Score:4, Insightful)
Oh, come one. Science is nothing like religion. The only people who claim so are those who do not understand science. Saying science is a religion is equivalent to saying dog grooming is a religion. Science is a process - a method of filtering out truths from nonsense. There is no "belief" about this process, no deep-rooted truths about the universe inherent in testing a hypothesis.
Maybe science is too hard for you. Not hard in the sense that the rigors of science -- the mathematics, the formulas, the process of experimentation are difficult -- but maybe the cold reality of the pure, beautiful process scares you. What if that's all there is?
Now I've had close friends die from suicides and murder and pointless accidents and late at night I've conversed with Him or Her or Them or whatever could comfort me then, but this is completely different from science.
Re:Fundamentalist materialism (Score:3, Insightful)
On the face of it, this is true enough - but I think what the original author meant (and at least what I infer when I hear those words) is "Science is a religion to some people."
Science is a process - a method of filtering out truths from nonsense. There is no "belief" about this process, no deep-rooted truths about the universe inherent in testing a hypothesis.
Yes, but there are people (such as James Randi, for example) who treat it as such. And (as such) science is
Re:Fundamentalist materialism (Score:3, Insightful)
Contrary to popular belief, science is not in the business of proving anything. What science
Re:Science *is* a religion *to some people* (Score:3, Insightful)
And I'm tired of being lectured on statistics and the scientific method, and how infallible it is, by people with no familiarity with either. (Note: this is not you, but other people.)
Science is a process. It is a method of attaching degrees of certainty to explanations of observed phenomena, of understanding our universe without bias or wishful thinking. The process ha
Oh Brother (Score:2)
Infrasound in movies (Score:3, Interesting)
And what's the big deal here...instead of the ghosts scaring people, it's the ghosts producing infrared sound that scares people.
I'm still scared of my Infrasound producing ghost-overlords.
Meters != Yards (Score:2)
Lord and his colleagues, who produced infrasound with a seven meter (yard) pipe and tested its impact on 750 people at a concert, said infrasound is also generated by natural phenomena.
Now I can understand telling someone a meter is about the length of a yard (or vice versa), but a.) not in a written science news article and b.) by the time you pile seven of these things on top of each other they are nowhere near equivalent sizes
Poor research produces ambiguous results (Score:5, Interesting)
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.
Re:Poor research produces ambiguous results (Score:3, Insightful)
Double-blind studies are necessary because the actions, subconscious or otherwise, of the experimenters can have an effect on the subjects, thus influencing results. I see no indications that this was a double-blind st
Not enough! (Score:3, Interesting)
I lived in a house a few years ago where at night you'd be asleep in a bedroom upstairs and hear footsteps walking around and down/up the stairs when you're sure it's no other person, your unalarmed overnight guests unanimously report being creeped out by some incident during the night, you see curtains moving and when you go to close the windows you find them firmly shut, your cat that was snoozing at the other end of the room and glancing at you ever few minutes suddenly looks freaked out and watches the the blank between you from left to right as if he's watching someone walking across the room, a vase falls and a voodoo doll pops out, you find unexplained knots in random places that apparently serve no logical function... etc etc.
Infrasound doesn't sound like a logical explanation to me.
Re:Not enough! (Score:3, Funny)
I don't believe in the supernatural. Instead, I have decided to believe in the superdupernatural, the hypernatural, and the googlenatural.
And as for that voodoo doll, I've been looking for that thing! I mean, you draw one pentagram on the floor, then you go to look for your voodoo doll, and then you can't find it. I hate when that happens...
experience bass... (Score:5, Interesting)
and heavy headaches comes along. No wonder people see ghosts under the influence of ultrasound
Heinlein's "Fifth Column"... (Score:3, Informative)
Reminds me of the old Pandora's Box (Score:5, Interesting)
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...
New Age? (Score:3, Insightful)
Honestly, since when did the subjects of ghosts and haunted houses suddenly become "new age drivel?" I grew up in a small Southern town where every family has at least two dozen ghost stories to tell with some going back two hundred years. While I realize that many "psychics" jump on the ghost bandwagon, please don't confuse their profession with the subjects they cover. Ghost stories are as similar to a new age concept as napalm is a food for deer.
Infrasound in film (Score:4, Informative)
If you are even in the mood for a quality film, I highly recommend this film.
Infrasound can make you sick - very sick. (Score:3, Interesting)
Imagine a hall big enough to park up a 737 or 2, incluind the tail, made of concrete block and hard flat surfaces - with a sprung wooden floor, 8-10 feet above concrete.
Now put ~20 1940-60 era valve HF tramsmitters on that floor, each with a 5hp 3-phase blower keeping things cool.
Result: lots of low frequency beat from the motors all running at slightly different speeds (they never run true, even when syncronous), unbalance fan rotors and a drum effect from the floor. Cap it off with high level white noise from the blade tips.
It was a recipe for a sick building. People working there spent most of their off hours sleeping. It wasn't unusual for staff to come off a week long shift and sleep the entire weekend till the shift started again.
While we knew high level infrasonics was probably the cause, there's no legal limits or recognised testing regime, so people put up with it...
Detecting Infrasound is easy and fun (Score:4, Informative)
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 [baudline.com]. 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!
Re:Can it be reproduced (Score:3, Funny)
Lord and his colleagues, who produced infrasound with a seven meter (yard) pipe
Sounds like something do-able. Just don't go trying to making an MP3 of it.
Re:Can it be reproduced (Score:2)
Re:Can it be reproduced (Score:5, Funny)
Re:Can it be reproduced (Score:5, Informative)
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.
Re:Can it be reproduced (Score:3, Funny)
BIG FUCKING DIDGERIDOO!!!
Re:Can it be reproduced (Score:5, Insightful)
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.
Re:Can it be reproduced (Score:4, Interesting)
they are still only using a 1/2 inch to a 1 inch throw woofer.
I messed with this back in high school. a 4 meter pipe with a 8 inch driver can rattle all the ceiling tiles out of a room easily and create a DB increase that was off the scale of the meter we had at 30hz and caused headaches in everyone in the room woth only 100 watts rms being used.
they are simply creating a resonance chamber for much lower frequencies... no pistons or other magic.
Re:Can it be reproduced (Score:3, Interesting)
The speaker is what interests me. You can get sub-20Hz responses but as you put it without a nice big resonant cavity, it won't go very far. I seem to remember reading that some cinemas were once equipped with low-frequency generators for special effects, but that meant one speaker per seat.
Re:Can it be reproduced (Score:5, Informative)
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
Re:Can it be reproduced (Score:5, Interesting)
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.
Re:Can it be reproduced (Score:4, Funny)
RTFA, all you need is a 7 metre pipe
Well, I guess I'll finally have to respond to some of that spam I've been getting.
Re:Can it be reproduced (Score:2, Informative)
Um, yes. Did you even bother to READ the story?
Frelling idiots with moderator points.
Re:Unanswered questions (Score:2, Informative)
n. pl. phenomena (-n)
1. An occurrence, circumstance, or fact that is perceptible by the senses.
2. pl. phenomenons
1. An unusual, significant, or unaccountable fact or occurrence; a marvel.
2. A remarkable or outstanding person; a paragon. See Synonyms at wonder.
3. Philosophy. In the philosophy of Kant, an object as it is perceived by the senses, as opposed to a noumenon.
4. Physics. An obs
Re:Well... (Score:2)
Well, this should make it even easier, do your exorcism mumbo-jumbo, and secretly just set up some very low fequency speakers in anti-phase to ambient sound. Hide them in the wall cavities and no-one will be the wiser. Hmmm...I wonder how much you could charge for that ?
Re:Oldish books... (Score:2)
Subliminal messages were (and still are) thought to be true and there were many anecdotes surrounding them as well. But they were proven untrue when studied.
This story is important because they have done a controlled experiment that offers more proof that this phenomena is real. Now we need others to do studies of their own to try and replicate the results. If replicated, th
Obligatory /. joke (Score:3, Funny)
ELF resonance??? You mean like Executable and Linkable Format? I didn't know old houses ran Linux! Imagine a beowulf cluster of those!
hehe U R TEH FUNNY!!! (Score:3, Funny)
You know, wavelengths on the order of meters. Like a small fraction of the size of a joist, or A-frame.
If a standing wave that could be induced on something like that matches the resonance mode of a cavity of air (attic, exterior room), you could get powerful propogation effects.
Elves, on the other hand, are squishy.