A Subwoofer Too Far (History Lesson)

Here is an item of historical interest. I recommend that you do NOT build such a device, for reasons that will become obvious.

:darkside:

In 1964 French scientist Vladimir Gavreau discovered and began to experiment on the effects of infrasound upon humans. He eventually prefected a device that created, and protection against, low frequency ("infra-", not "sub-") sound that could injure and (conjectured) perhaps kill humans. He received patents. It's not known if such devices have ever been used in warfare/ covert actions.

Here is where I learned of it: the series (on Netflix) "Dark Matters: Twisted but True" episode 5, "The sound of death" (2011). This is a great series, hosted by John Noble, an actor whom I erroneously thought was one of the shadowy guys from "X-files" but no. He has an impressive resume, but did not appear in the X-files. He does play the mad scientist in "Fringe" (which I heartily recommend as a good X-files replacement). Sorry if I come off like a Netflix shill but hey, that's where I get a lot of my video entertainment!

You can also Wiki "Gavreau" and no doubt find other sources.

An acoustic weapon appears in Ayn Rand's famous "Atlas Shrugged." If you're familiar with this novel, you won't accuse Rand of knowing much about science. It'd be great if Galt's motor or Rearden Metal really existed, however! It is my opinion, and based upon the Burroughs (fiction?) quoted in the wiki, that while such a weapon is no doubt possible, it would be immensely inefficient. But still, think of the low frequency response! :)
 
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The only application of infra-sonics anywhere approaching "The darkside" has been the communications systems for submarines....using infrasonics. By this measure all humans (Nevermind all Ocean dwelling mammals) who have swam the open Oceans should have died some decades ago up till the present. Pure fantasy this acoustic "deathray" stuff.


_____________________________________________________Rick.........
 
Don't earthquakes produce massive amounts of infra sonics?

I was thinking of this just after I wrote my entry. The energy of naturally generated infrasonics is far far more than any energy possibly generated by humankind. ...Still, no massive deaths of marine life.


_______________________________________________Rick..............
 
Here is an item of historical interest. I recommend that you do NOT build such a device, for reasons that will become obvious.

:darkside:

In 1964 French scientist Vladimir Gavreau discovered and began to experiment on the effects of infrasound upon humans. He eventually prefected a device that created, and protection against, low frequency ("infra-", not "sub-") sound that could injure and (conjectured) perhaps kill humans.

"A whistle 1.3 meters in diameter produced an infrasonic pitch of 37 cycles per second. This form violently shook the walls of the entire laboratory complex, though its intensity was less than 2 watts infrasonic power."
From Deadly Sounds - Dr. Vladimir Gavreau

It is of historical interest how much overstated the effects of "infrasonic power" were by the good doctor.

2 acoustic watts is 123 dB SPL.
37 Hz is not considered "infrasonic" this century.

Josh Ricci's Gjallerhorn can do an order of magnitude louder than that indoors an octave lower.

My Keystone sub, half the size of the Gjallerhorn, can do well over 133 dB (more than an order of magnitude louder than Vlad's "deadly sounds") at 37 Hz in a small room.

In any city in the world you can hear automobiles going by with LF at much higher SPL inside than anything achieved by Vladimir Gavreau. They may be annoying, but they certainly are not deadly.

If loud LF sounds were deadly, every astronaut would have succumbed on the launchpad, where levels of 150+ dB at a few Hz are experienced on every takeoff.

Art
 

iand

Member
2007-02-05 10:58 pm
London
"A whistle 1.3 meters in diameter produced an infrasonic pitch of 37 cycles per second. This form violently shook the walls of the entire laboratory complex, though its intensity was less than 2 watts infrasonic power."
From Deadly Sounds - Dr. Vladimir Gavreau

It is of historical interest how much overstated the effects of "infrasonic power" were by the good doctor.

2 acoustic watts is 123 dB SPL.
37 Hz is not considered "infrasonic" this century.

Josh Ricci's Gjallerhorn can do an order of magnitude louder than that indoors an octave lower.

My Keystone sub, half the size of the Gjallerhorn, can do well over 133 dB (more than an order of magnitude louder than Vlad's "deadly sounds") at 37 Hz in a small room.

In any city in the world you can hear automobiles going by with LF at much higher SPL inside than anything achieved by Vladimir Gavreau. They may be annoying, but they certainly are not deadly.

If loud LF sounds were deadly, every astronaut would have succumbed on the launchpad, where levels of 150+ dB at a few Hz are experienced on every takeoff.

Art

You could also ask Tom Danley why he isn't dead (or in any way damaged), having stood in front of his sonic boom simulator while it was putting out enough energy (several kW acoustic power) in the single-digit-Hz region to move the wall of a wooden-framed house in and out by a foot or so. I seem to remember he said that contrary to conventional wisdom you can hear 3Hz but the threshold of audibility was something around 150dB SPL...
 
If memory serves, there was an article in The New Scientist some years ago about a low frequency weapon developed for the military , unfortunately I can't find it in the archives but it must be there somewhere. It was not a loudspeaker however, it looked like a large steel mortar tube and generated sound by detonating a fuel air mixture much like an internal combustion engine and was said to induce nausea and an uncontrollable loosening of the bowels. The brown note as it were.
 
Well for anything like this to be effective you need energy to be transfered. If the wavelength is wrong then not much will happen. Get it right so that a resonance develops and you could probably watch humans die. Or just make it much much louder.

I wonder if the Danley wall shaker had the frequency set just right so that the wall vibrated in sympathy with the tone.
 

DrDyna

Member
2007-05-17 11:34 am
I could see extreme SPL at low frequencies harming someone who might already have health issues, if we're talking about levels high enough to actually exert pressure on your body. I mean, we can see effects with barometric pressure changes, or swimming too deeply into the ocean unprotected, but the logistics of building a sonic device capable of exerting enough pressure on a (healthy) human body seems tough, unless you were to specifically build a device with that in mind...lets say, 16x LMS 5400 Ultra drivers mounted facing inward in a 2x2x12 square tube...then standing inside it while someone played 10 cycle sine at xmax.

As long as you're healthy, or you specifically want to spend tens of thousands of dollars building something that could hurt a person, we probably don't have anything to worry about.
 

iand

Member
2007-02-05 10:58 pm
London
Well for anything like this to be effective you need energy to be transfered. If the wavelength is wrong then not much will happen. Get it right so that a resonance develops and you could probably watch humans die. Or just make it much much louder.

I wonder if the Danley wall shaker had the frequency set just right so that the wall vibrated in sympathy with the tone.

Yes it was. But IIRC he also did sweeps from a couple of Hz up to fifteen Hz or so with himself sitting in a sound field of several thousand acoustic watts with no ill effects, bowels included.

All the references on the web to sub-audible acoustic weapons and "brown notes" are basically just that -- crap.

(tried tracking down more stuff from Tom, maybe hearing threshold was 130db at 3Hz? Either way he's spent more time than anyone else on the planet subjecting himself to these sounds, if he says the "brown note" is a myth I for one believe him)
 
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Yes it was. But IIRC he also did sweeps from a couple of Hz up to fifteen Hz or so with himself sitting in a sound field of several thousand acoustic watts with no ill effects, bowels included.

All the references on the web to sub-audible acoustic weapons and "brown notes" are basically just that -- crap.

(tried tracking down more stuff from Tom, maybe hearing threshold was 130db at 3Hz? Either way he's spent more time than anyone else on the planet subjecting himself to these sounds, if he says the "brown note" is a myth I for one believe him)
Funny, I was under the impression The New Scientist was a reputable publication, your credentials obviously carry more weight.
 

iand

Member
2007-02-05 10:58 pm
London
Funny, I was under the impression The New Scientist was a reputable publication, your credentials obviously carry more weight.
And which particular New Scientist article was this?

Another one which recirculated the same old unsubstantiated rumours -- the NS researchers are not by any means infallible -- or some genuine proof?

If it was genuine, I'd love to know what sound source was used to prove it, since Tom's sonic boom simulator wasn't up to the job...
 

iand

Member
2007-02-05 10:58 pm
London
I described it.

Nope, you said you thought you remembered it ;-)

And the military has wasted a lot of money over the years on bird-brained ideas for fantastic weapons that didn't work in real life. Bet you this was one of them...

Sign in to read: Not a sound idea - 20 March 1999 - New Scientist

http://www.newscientist.com/article/mg17223216.900-sound-blasting.html

Sign in to read: How low can you go? - 17 July 1999 - New Scientist

So 220dB causes death? Not surprising since 174dB is 1 atmosphere SPL, which means 220dB is a 3000psi pressure pulse, which means you're very close to a big explosion which would literally pulverise you.

I expect the numbers impressed the gullible non-technical people who agreed to finance the development though...
 

DrDyna

Member
2007-05-17 11:34 am
I'm perfectly relaxed, even when the same old "brown-note" ******** gets recycled as "fact" once again. It really ought to be down on one of the urban myths websites -- oh hang on, it is...

Well, their experiment was slightly questionable, but I still think the results agree with what one would think. There isn't a magic note that can make you crap, but I'd imagine that if you were inside a pressure vessel and subjected to enough force, it might happen, but not at one magical note.

As an aside, the pressure would probably also cause other nasty things, like hemorrhage / stroke / suffocation on one's own vomit / etc.