# Haunting using infrasound?



## UnderMan (Aug 23, 2007)

Television is, sometimes, an unexpected source of a possible good idea for Halloween.

I heard that infrasound (frequencies below the normal hearing range of human beings - below 20Hz), may be responsible for the feeling of another presence in a reportedly haunted house. Infrasound has been detected and measured in some haunted house cases.

This gave me the idea of wanting to use it in my haunt, so I did a little research on the internet. Good old internet, a good source for research.

Build an infrasound generator, either electronically or mechanically, but a resonant chamber is the key to get proper acoustics out of it.

If you are good at electronics you could build a sinewave generator capable of producing such frequencies, hook it up to a sub-woofer, and run it through a resonant chamber.

If you wish to mechanically make a generator, have a slow motor, under 1/3 rpm, hooked to a cone which is secured to a frame via fabric for stability and cushioning. The cone will compress and expand the air around it, not unlike a speaker. Then run it through a resonant chamber.

The resonant chamber can be a wide plastic drain pipe, but it has to be 1/4 of the wavelength long, to ensure maximum effect.

The following is some information I have found on various websites during my search:

*INFRASOUND*


Very low frequency, below 20Hz (human range: 20Hz - 22KHz)
You feel the frequencies rather than hear it. From as low as .0001Hz.
Elephants and whales communicate at infrasound frequencies.
Caused by natural sources, such as wind, earthquakes, eruptions, etc.
Man made frequencies include manufacturing plants.
Attributed to feelings of an unseen presence (ghostly).
Anxiety, fear, anger, extreme sorrow, chills, nervousness, and revulsion are feelings reported by a test audience at a musical concert with infrasound included in some music.
18.98Hz is the natural frequency of the human eyeball, making the eyeball vibrate slightly which could possibly cause hallucinations.
Sustained exposure to infrasound can be detrimental to sensitive people.
7Hz purportedly causes people to go crazy.
The body cavity has a natural frequency of 3 - 7Hz.
Apparently the anal sphincter has a resonant frequency of 10-15Hz, maybe this is the "brown note" frequency range, possibly causing a person to defecate. Possible use would be as a crowd control measure.
Is transmitted most efficiently via solid objects and water as opposed to air.
Best results obtained with a ¼ wavelength resonant chamber.
Experiment with sine, square, and saw tooth waveforms.
 I haven't tried experimenting with it yet, as I just found out about it, but I plan on doing a bunch of secret tests on family. If anyone makes one and notices the reaction of people, I'd be delighted to hear about it.


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## RookieSpooker (Jul 23, 2007)

I heard that if you get just the right resonance, EVERYONE CRAPS THEIR PANTS. FUUUUNN!!


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## darryl (Mar 23, 2006)

Man i saw one of these for sale on some website just last week but can't remember were. Anyone???


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## Xpendable (Sep 19, 2006)

Couldn't you just use a computer to generate sounds below 20hz? I could be wrong, but I think most computers can generate sounds below and above the range of human hearing.


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## frstvamp1r (Nov 5, 2006)

Someone already markets a "fear generator"...here is the link...
http://monster-tronics.com/index.php?cPath=22&osCsid=4983cb793d3c63773a6deea4534b4f76


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## UnderMan (Aug 23, 2007)

I tried, I have a little program that will allow you to choose any frequency, but sounds below 36Hz won't play. I wanted to see what effect it would have on me if I went down to frequencies below 20Hz.

I guess you could build an output device and toggle a port on and off, but it would be a square wave.


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## edwood saucer (Aug 21, 2006)

I love that - $950 for a gadget you think should work - might work - but who the heck knows!

What a hoot - I'm excited to see where this thread goes though - the technology is interesting.


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## UnderMan (Aug 23, 2007)

Thank you for the link, but the generator is way out of my price range. I am an electronics technician and I should be able to build one myself, I was hoping that a subwoofer would have the proper frequency response though. Might have to build that and the amp too. Lots of work ahead.


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## UnderMan (Aug 23, 2007)

Mythbusters have already busted that myth. I can't remember if they went into the infra-sound range however.

I should email them and see if they would do the "fright" experiments on their unsuspecting crew. Set up a story or scene to get them on edge first and have the generator working on them during the set up and definately during their "haunted exploration".

That would be an episode I'd have to record.


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## JohnnyL (Aug 17, 2006)

Doesn't it give some people headaches?


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## Revenant (Mar 17, 2007)

Mythbusters tested the "brown note" theory and busted it, but they're not really exhaustive in their research. Many of the other effects are documented though. At certain frequencies heavy infrasound causes the organs to vibrate against each other and hemorrhage. Would be a helluva ghastly weapon. A long time ago... I forget, I think it in the 60's... some military scientists built a prototype infrasound organ pipe called the "Little Monster" and damn near killed everyone in the research facility. Research was shelved when they realized you can't direct it, thus you can't safely test it.

If you can find it, check out a recording of "Sonic Attack", by Hawkwind. It's sort of their idea of a wartime PSA spot for what to do if under sonic attack; they apparently did a bit of research because the symptoms they list are accurate for dangerous infrasound. Uber creepy.

Do not panic... think only of yourself...


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## UnderMan (Aug 23, 2007)

I haven't read anything about it causing headaches, but if I get the thing working, probably after Halloween, I'll let you know. I am very prone to headaches for over a year and a half now. I would be a good test subject in that particular experiment. I can hardly wait to begin building it. 
I have to find a good subwoofer capable of .01Hz to whatever top response it has to be up to 20 Hz.


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## UnderMan (Aug 23, 2007)

I believe they were pumping something over 140dB of infrasound in order to cause such destruction, anything over 140dB at any frequency is bound to have detrimental effects.
The information I got off the internet was that they were using 120dB or a bit more. I would start low and work my way up to 110dB or as much as 120dB, but I won't dare go above that. We occupy our haunt and I must think of us more than the patrons, who will only be subject to the effect for a relatively short period of time. Depending on the lineup, which we've had people wait up to half an hour to get in.


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## UnderMan (Aug 23, 2007)

It would be a great addition to any haunt. People are both excited and apprehensive (a little scared) while waiting in line to enter a haunt. It would be wonderful to give them a sense of panic to go with it. My gift to my patrons. See, what a nice guy I am.


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## Long_Tom (Oct 7, 2006)

120 dB is sufficient to cause hearing loss. Assuming you don't want to actually injure anyone in any way (and hearing loss does count as injury) I'd advise against it.


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## UnderMan (Aug 23, 2007)

Advice taken. I remember that prolonged exposure 120dB cases hearing loss, and since we will be exposed to the effect for several hours on Halloween I will make sure we are below that threshold.

Thank you.


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## BoysinBoo (Dec 10, 2007)

I AM THE THREAD RESSURECTOR!

Has anybody tried this? I think I've go the parts to assemble. I'm gonna start playing with it soon.


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## Otaku (Dec 3, 2004)

I watched a "South Park" the other day in which the "brown note" theory was used in the story. The kids wound up making everyone on the planet crap their pants simultaneously. Wet costumes at a haunt are usually a sign of a successful scare - I don't know about brown ones, though...


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## Fiend4Halloween (Aug 28, 2008)

They were testing this in prisons to try of a less physical way of removing prisioners from their cells. They included a green laser light that expanded to about a 3' area to illuminate the area that would be affected. It would drop the prisoners immeditatly but caused symptoms from naseua, to diarrhea, to headaches that lasted for days, so they stopped the testing and nixed the project.


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## HalloweenBob (Dec 17, 2008)

I started experimenting with this 2 years ago. I never saw the site that was highlighted in this thread, however. I created a 19Hz tone wav file that you can download if you want here:

http://rewindshow.com/haunt/19Hz5min.wav

Right click on the link and choose "Save Target As" from the menu.

Here's another way to reproduce the infrasonic frequencies:






http://www.eminent-tech.com/main.html

http://www.hawthorneaudio.com/forums/viewtopic.php?f=2&t=1454&start=615

Interestingly enough, when I play my 19 Hz wav file, I can actually hear it. They say that the human ear can hear down to 20 Hz. I guess that's an average. Anyway, it is faint and I probably would not recognize it as sound if it were playing in the background. I would just hear it as natural ambiance of the area.


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## RoxyBlue (Oct 6, 2008)

Didn't "South Park" do an episode on that brown note thing?

If it's true about the defecation thing, it might not be the most favorable feature for a haunt


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## Otaku (Dec 3, 2004)

Haunt Master Products had an infrasound CD for sale for a couple of years. Haven't seen it on the web site for a while, though.


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## Otaku (Dec 3, 2004)

RoxyBlue said:


> Didn't "South Park" do an episode on that brown note thing?
> 
> If it's true about the defecation thing, it might not be the most favorable feature for a haunt


Yeah, the note was played at the end of the "4 Million Kid Blow".


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## Revenant (Mar 17, 2007)

Aw, dammit Bob! I played that .wav file at work and just pooped myself. Way to go, ace. I'm sending you my dry cleaning bill.

On the upside, it was pretty scary.


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## Dr Morbius (Sep 21, 2004)

It sounds like a truck idling in the distance to me. If I heard that played over a proper amplifier, I would interpret it as some kind kind of equipment running. Interesting.


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## hedg12 (Jul 6, 2008)

I've been intrigued by this idea for quite a while. I remember way back in my misspent youth hanging out at car stereo competitions occasionally feeling a strange apprehensive feeling that could be attributed to this phenomenon. Or it could have been the burritos... Anyway, a couple of things I do know. In order to generate ULF at a volume loud enough to create the desired effect, you'd have to move a _lot_ of air. If you're planning on doing it with traditional loudspeakers, you're looking at multiple 15 or 18 inch subwoofers in very large enclosures, with large, expensive, electricity guzzling amplifiers driving them. I find the thought of non-traditional tranducers intriguing, but really have no idea what would work and what wouldn't.

I'd also be concerned with the effects of prolonged exposure to the ULF. I don't think your patrons exposure time would be an issue, but I'd be worried about any actors working the haunt. The damaging effects from loud noises are cumulative.


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## grim reaper (Aug 18, 2005)

i dunno wether they have this in the states but out here in england shops are starting to use something like this its plays a high pitched noise that only youths can hear and its suppossed to annoy the heck out of you so you dont hang around outside shops. personally it would just put me of shopping there, im not one to hang about outside causing havok.


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## Scottzilla (Jun 13, 2007)

HalloweenBob: Yeah it would be fun to figure out how to build one of those rotary subwoofers. 

It's possible that when you were listening to your 19hz you were hearing some harmonics instead of the fundamental frequency.

I did try the "fear generator" thing once, but I don't really know if it worked. I didn't notice much. I just hooked a function generator up to a 15" sub. I know my amp and speaker weren't rated for anywhere as low as I was running it, but it was doing something. At the super-low frequencies I could still see the cone moving in and out. Perhaps not audiophile accurate but it still moves air. It's possible it just wasn't moving enough air. Must get bigger subs.

I'm pretty sure the theory is sound though because I have been creeped out for no reason at times then later realized there was a truck rattling the building I was in or something.


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## Rocky666 (Oct 15, 2010)

Another way to produce infrasound frequencies is by using binaraul beat frequencies...basically, any two tones, played in stereo will produce a third phantom rhythmic tone equal to the distance between the two original frequencies.

It is therefore possible to take multiple tones, say 12Hz and 19Hz, and play them simultaneously and create a 7Hz phantom tone in the center of the stereo field. That phantom tone is completely generated by your mind and with time causes brainwave entrainment which can also be used to influence mood. 


> > 40 Hz Gamma waves Higher mental activity, including perception, problem solving, fear, and consciousness
> 
> 13-39 Hz Beta waves Active, busy or anxious thinking and active concentration, arousal, cognition
> 
> ...


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## Rocky666 (Oct 15, 2010)

Oh, and sorry for resurecting a 3 year old thread as my first post


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## austenandrews (Aug 22, 2010)

Your mad science intrigues me.


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## Rocky666 (Oct 15, 2010)

HalloweenBob said:


> *Interestingly enough, when I play my 19 Hz wav file, I can actually hear it. *They say that the human ear can hear down to 20 Hz. I guess that's an average. Anyway, it is faint and I probably would not recognize it as sound if it were playing in the background. I would just hear it as natural ambiance of the area.


The actual lowest frequency people can hear is determined by the size of their head/how far apart their ears are. Any wave with a physical wavelength wider than the space between your ears is inaudible. You might just have a big head


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## GhoulishGadgets (May 13, 2010)

I've commented on this somewhere before, maybe this forum...

I've found the best way to play with this is using Car Amplifiers, as they can get to some real nice low frequencies - and at a decent price.

you can probably buy infrasound recordings etc, I used a cheapy signal generator, but electronics is my thing, so had it kicking around... you can get them cheap online or as a kit to save even more money

(I also had some big speakers kicking around, you need a decent big speaker / sub-woofer with large cone size to move enough air about, mine are about 15" I think)

I modulated mine, from about 10 to 20 hertz over about 5 seconds, mixes with a foggy haze and a drop to complete darkness was an interesting effect

Si


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## Rocky666 (Oct 15, 2010)

Best results would be from a 21" speaker in a folded horn cabinet....or rather, multiple 21" speakers in horn cabinets such as these bad boys from funktion one...










Dual 21" speakers in a tuned enclosure.

Funktion also makes an "Infrahorn" which supposedly boosts the 33Hz frequency of their infrabass speakers by 10-12db (which is a massive boost)










Also, there are sweet spots and dead spots depending on speaker placement in the room. Some experimentation with moving the location of the subs will move the sweet spots around to the intended area.


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## Rocky666 (Oct 15, 2010)

PS, those are not cheap speakers, LOL....about $4,800 each, not including the massive 2k watt amps required to push them and...probably heavy/high amps power pre-installed in the building.


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## Mortarlover123 (Oct 4, 2009)

why not try a tactile transducer mounted on a free floating board or metal as a resonator and create low frequency levels


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## Rocky666 (Oct 15, 2010)

Honestly, I just don't know anything about such transducers. How accurate are they at reproducing a sound?

The resonant frequency of the soundboard would also come into play a bit I am sure.

BTW, you can build a folded horn sub for a few hundred $ instead of buying one for several thousand....lots of DIY folded sub projects on the web...


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