Mythbusters...

[Jay-qu]

wouldnt say enthusiasist, but I did find that episode rather entertaining - and yet they didnt fully satisfy what I would say as been busted. As you said they didnt try any frequency below 5Hz, maybe its a conspiricy and they where contacted by a certain government and told (threatened) no to go below 5Hz or at least show it on T.V... :rolleyes: Who knows, it could be true :hihi:

[Turtle]

___I Googled "brown noise" & found mostly articles referring to Brownian Motion. I then Googled "sound weapon" & found this little tidbit which is likely where I read the whistles stuff before.

 

http://www.borderlands.com/archives/arch/gavreaus.htm

 

Quoting from the link:

"The main resonant frequency of these pipes occurred in the "range of death", found to lie between three and seven cycles per second. These sounds could not be humanly heard, a distinct advantage for a defense system. The effects were felt however. The symptoms come on rapidly and unexpectedly, though the pipes were operating for a few seconds. Their pressure waves impacted against the entire body in a terrible and inescapable grip. The grip was a pressure which came in on one from all sides simultaneously, an envelope of death. "

 

Aha! :) :hihi: :) :rolleyes:

[DFINITLYDISTRUBD]

ALRIGHT youngins! Now yoove dun it ! yer in trubble now! HEE HEE!

Remember the last time you were sick. (you know movements from both ends!)

The brown noise is likely to be right aroung the same frequency at which your insides were churnin. :rolleyes:

lovely thought huh!

[CraigD]

___I Googled "brown noise" & found mostly articles referring to Brownian Motion.

To avoid this ambiguity, try searching for the phase “brown note”. Or just go straight to the Wikipedia article “Brown note”.

 

My quick take on the subject is that its mythos is large: before I stopped reading, I found half a dozen separate account by people claiming to have played the dire tone on ordinary stereo of instrument horns, sending a room of people on a mad, smelly rush for the toilet. A couple claimed to have induced the effect using PC subwoofers. I’m pretty confident these accounts are either outright fabrications, or reveal some sort of bizarre peer-induces psychosomatic effect – these consumer market speaker horns don’t produce nearly enough <20 hz sound pressure to do much gut-shaking.

 

Oddly enough, less than 12 hours ago, I was hanging out with a bunch of musician/audiophiles who happened to have a 4x 18” bass speaker cabinet. Someone mentioned the brown note, and got me to attempt to produce it with the available audio equipment, an absolutely gorgeous 32-channel mixer with a rack full of effect boxes and other stuff of which I have no comprehension, none of which seemed at all useful in generating the requested subsonics.

 

Not to be defeated, and with a geek reputation to uphold, I took stock. I had on hand:

• A guitar tuner that’ll generate tones, but only down to about 50 hz
  
• A nice vinyl record turntable with a good-quality magnetic cartridge.

At home, where I have the usual hobbyist assortment of DC gadgets, the easiest way to generate subsonic frequency sound (is that an oxymoron?) is to connect a DC power supply to a mechanical rheostat with a big knob, and that to the biggest speaker on hand. Moving the knob moves the speaker cone. I can move my hand fast enough to generate pretty smooth movement anywhere from 0 to about 10 hz.

 

But I wasn’t at home. Fortunately, I was in a barn not far from someone’s home, so mounted an expedition to his huge selection of vintage vinyl to search out the most warped disk he had, finding one with a nice single bend giving it 2 up-down cycles a revolution. Back in the barn, it was easy to hand-turn the disk on the turntable, with the needle in the records recording-less “end gutter” (or whatever the correct term for the innermost grove on a record is) to make the 4 18” speaker cones wobble what looked like about an inch with each half turn. Handspinning at 150 RPMs, (not too hard if you’re at least half sober) produces the famous 5 hz note.

 

Results?

The speakers look cool at the edge of visible/blurred movement. They’ll blow out a butane lighter if you get one within a couple feet of them. They mess up your singing if you try to sing in front of them. A couple of people said they made them feel creepy, and everybody agreed you could feel them. No induced rush for the bathroom, collapsed lungs, ruptured eardrums, exploding eyeballs, or (thank you patron saint of pro audio) damaged speakers.

 

We were limited to how much power I could use by the “tap” sound the record makes each revolution as the end gutter passes the place where the spiral grove enters it. Turned high enough that the subsonics were perceivable, this tap was near painfully loud, and likely not good for the speakers. In retrospect, I think this is a good thing, or somebody could have been hurt.

 

The Mythbusters did a much better job than we did, but, as the show says, they’re professionals. It also says something about not trying anything at home, but obvious we’re not paying much attention to that part.

 

I’m personally convinced that a committed hobbyist could put together a subsonic device that would generate enough pressure to hurt or kill someone. Whether it could be fine-tuned to loosen their bowels before doing more severe damage, I don’t know. I’m pretty sure you’d blow the cone on an pro-quality 18” speaker before doing any tissue damage, so some sort of special speaker would be required. Sounds like something best left to the millitary.

 

Recommendations?

If you’re the vicious sort of person who wants to make unsuspecting victims poop themselves, try 1 part rum to 4 parts magnesium citrate distilled down to 1/4 its over-the-counter volume. Then stay away from me, and seek therapy.

[CraigD]

An interesting myth I’ve come across (at the same jam/party that I encountered and attempted to reproduce “the brown note”) is that the THX system specification requires high-power sound output into the subsonic range (< 20 hz).

 

It took a lot of googling, and I still haven’t found a simple, authoritative source, but I’m lead to believe that the THX standard only requires high-power output down to 36 hz.

 

We can all go to the movies reassured that evil movie pranksters will not use the theatre’s THX-certified equipment to assail us with the brown note.

 

Myth: BUSTED. (weakly)

[Turtle]

___Nice work Craig! I accord you the honor of High Lord Experimenter! (How's that spinning disk machine coming HLE ? :hihi: )

___On the Brown Note, I point out the French guy I refereenced earlier says the "death zone" is 3 to 7 Hz. Several experimental concerns I have: 1) The exact Brown note may not have an integral value, or it may require more than one note in a harmonic or chord, or it may lie lower than these experiments. The bowel is irregular in shape & so likely has a number of resonant frequencies. 2) The effect may require a more lengthy exposure to come to full release; once in resonant oscillations an object continues to gain energy from the input source without that source increasing power. The singer & the wine glass example, which Mythbusters also tested & found true, illustrates my point.

___Anyway, rock on! :rolleyes:

[DFINITLYDISTRUBD]

I'm not quite sure what THX is but if it's a sound system it's pretty crummy!

37hz!?!?!

I've got pretty old but high quality sound gear that has a frequency responce of 15hz-25,000mhz most of which are over 35 years old!

 

I've got my own technique and equipment for brown note attempts... the heart of which is the dialing mechanism from an old mechanical dial telephone. Basically all it is is a points breaker system (it looks really fancy and complicated but that's all it is...a simple points breaker system.) This is linked to a step-motor with a speed controll and a reduction gear box. The breaker is linked to a car battery on one side and speaker cables on the other which are in turn linked to a DC solinoid (100lbs plus force capable) which strikes the bottom af a wooden chair. When I built this rig the idea was that this would result in more direct transfer of oscilations to the bowel. It was uncomfortable but didn't get results even below 1 hz nothing at 0.5, 0.25, or even 0.125hz. I started a 120 hz and worked my way down it simply did not work. (It was extremely uncomfortable though!!!:) Kind of like being kicked in the bum over and over and over again...bruising did occur!!!;) ) And incidently Testes don't particularly like this type of treatment either!!!!!!!!!!!!!!!!!!!:)

[CraigD]

I'm not quite sure what THX is but if it's a sound system it's pretty crummy!

37hz!?!?!

THX is mostly a certificate that you can get for a listening room like a movie theatre, or a recording room. If THX certified recording is played in a THX certified room, it should sound like it was intended to sound.

 

Just because the movie leader says a film was recorded in THX, doesn’t mean the theatre in which it’s played is THX certified. Hardly any older theatres, and, in my experience, few new ones, are. An easy clue that a theatre is not is if the floor is concrete or carpet on concrete, rather raised flooring, though a lot of raised-floor theatres aren’t THX certified. THX has this search site that can tell you which theatres in a given state or country are THX certified. Several lower-population states don’t have any.

 

It’s not that THX – or practically any high-sampling rate or analog sound system that uses electromagnetically driven speaker horns – can’t produce frequencies below 37 hz, but that the specification doesn’t require that they be capable on generating a minimum sound pressure (decibels) below that. Since very few sound recordings call for high-power low-frequency sounds, this shouldn’t be a practical shortcoming.

 

It seems very hard to generate large sound pressures at low frequencies, since to build up a lot of pressure require moving the speaker fast, but to keep the frequency low requires it move slow. This needs something like a fast increase in voltage followed by slow decrease, but it’s hard to keep the speaker for vibrating at its own frequency, making a series of “taps” rather than the desired deep, smooth tone.

I've got my own technique and equipment for brown note attempts... the heart of which is the dialing mechanism from an old mechanical dial telephone. …And incidently Testes don't particularly like this type of treatment either!!!!!!!!!!!!!!!!!!!;)

DD, you are ultra-cool! I wish I could see your toys!:)

[Drip Curl Magic]

___I have watched a few episodes & I have a problem with at least one; the show on Brown Noise. They concluded it was a myth, but they never tried any frequencies below 5HZ & further, I don't think standard speakers will suffice for this experiment. I have read quite a bit on this over the years, from Tesla's vibrating platform experiment which sent Mark Twain running for the john, to French experiments with sound canon that cause internal organs to vibrate against one another causing hemhorage & death.

___The problem seems not that it doesn't work, but that it can't be aimed & so kills the operaters as well. I saw one form of a Brown Noise generator that was a giant concrete "whistle" & apparently effective. Any other Brown Noise enthusiasts out there? :)

 

yeah, you're definately not able to reach the brown note with any normal speakers. You need to specially design some sort of crazy vibrating apparatus.

 

From what I've heard, the brown note was used by governments in other countries as a riot control. But I don't know if this information is plausable or not.

[Queso]

there's some info about it in this thread, just back there

[Drip Curl Magic]

there's some info about it in this thread, just back there

 

 

yap, saw it after I posted.

 

still didn't see anything about my riot control claim.... which is what I was wondering about.

[Zythryn]

For the second show - they tried to get an old car to flip over having its prop shaft break off and peg into the tarmac. They tried to do it remotely, and they just could not get the prop shaft to come off. Eventually, they did manage to shear it, but it didn't peg into the road the way they planned it. So, obviously, they assumed its impossible.

 

Idiots.

 

 

Boerseun, I feel I need to take you to task on this part of your statement.

They did get the shaft to drop and hit dead center in their manufactured pothole.

 

The reason they said the myth was busted, was because while the shaft did kick the back of the car a few feet of the ground, the shaft also penetrated the trunk. They concluded that additional speed would simply push the shaft further into the trunk. This seems reasonably sound although if a cars body was reinforced so the drive shaft couldn't penetrate the trunk as easily then I could see that happening.

 

I centainly wouldn't call them idiots. Sure, they make mistakes, and as already mentioned, they revisit some of the experiments if people write in and point out flaws in their conclusions.

 

While this is not a classroom level science class, I think the show is entertaining and is one of the few shows that brings science to the populace in an entertaining and fairly popular fashion.

 

If you have personal experience of the dropped shaft causing a car to flip, drop them an email and let them know. The will check into it and see if they can reproduce it (heck Adam was really hoping it would work and would love to have another shot at it:)).

 

Mark

[DFINITLYDISTRUBD]

THANX!!! I appreciate the enthusiasm!

[anglepose]

i love watching the explosions they rock i loved the confedderate rocket show

[DFINITLYDISTRUBD]

My fave explosion was the tree cannon.

They are starting to frustrate me though...more and more I'm yelling at my TV.

EX. the swing no it is not possible to go all the way around on a swing supported by chains!!!!!dummies!!!!!!I've tried... you hit a certain point and you get the drop-yank effect!!!!!!!!!!! (the chain slackens you start decending and whump the chain goes taught again) More and more they are resorting to myths easilly resolved with a little common sence!!!!!!!!!!and it sucks!!!!!!!!!!!!

 

As for the driveshaft polevault it could happen...I had a 71 dart that was rolled over by the driveshaft when a universal joint failed (for those unfamiliar with autoparts a universal joint is a flexible coupeling that allows the drive shaft to "flex" with changes in suspension geometry)

 

Then there's the police car axle yank- newer police cars have much tougher suspensions. If they had used a 50's or 60's vintage police car (or family sedan similar too one) there's a reasonable chance that they would have succeeded as these vehicles did not have as robust a suspension or frame. Apples and oranges!!!!!!!!!!Incedently in the movie they got this idea from, the rear axle was on sliding rails on the frame.