A Subwoofer Too Far (History Lesson) - diyAudio
Go Back   Home > Forums > Loudspeakers > Subwoofers

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 24th May 2013, 06:09 PM   #1
diyAudio Member
 
Soldermizer's Avatar
 
Join Date: Feb 2012
Location: Tamper, FL, USA
Default 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.



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!

Last edited by Soldermizer; 24th May 2013 at 06:14 PM.
  Reply With Quote
Old 24th May 2013, 06:31 PM   #2
diyAudio Member
 
Richard Ellis's Avatar
 
Join Date: Sep 2006
Location: Mar del Plata, a BIG seasonal getaway city, can see the Ocean from our residence.
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.........
  Reply With Quote
Old 24th May 2013, 07:44 PM   #3
cbdb is offline cbdb  Canada
diyAudio Member
 
Join Date: Oct 2008
Location: Vancouver
Don't earthquakes produce massive amounts of infra sonics?
  Reply With Quote
Old 24th May 2013, 10:16 PM   #4
diyAudio Member
 
Richard Ellis's Avatar
 
Join Date: Sep 2006
Location: Mar del Plata, a BIG seasonal getaway city, can see the Ocean from our residence.
Quote:
Originally Posted by cbdb View Post
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.


_______________________________________________Ric k..............
  Reply With Quote
Old 25th May 2013, 06:34 PM   #5
diyAudio Member
 
Join Date: Jan 2008
Quote:
Originally Posted by Soldermizer View Post
Here is an item of historical interest. I recommend that you do NOT build such a device, for reasons that will become obvious.



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
  Reply With Quote
Old 27th May 2013, 12:22 PM   #6
iand is offline iand  United Kingdom
diyAudio Member
 
Join Date: Feb 2007
Location: London
Quote:
Originally Posted by weltersys View Post
"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...
  Reply With Quote
Old 27th May 2013, 01:25 PM   #7
diyAudio Member
 
Join Date: Aug 2011
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.
  Reply With Quote
Old 27th May 2013, 01:34 PM   #8
diyAudio Member
 
5th element's Avatar
 
Join Date: Oct 2002
Location: England
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.
__________________
What the hell are you screamin' for? Every five minutes there's a bomb or somethin'! I'm leavin! bzzzz!
  Reply With Quote
Old 27th May 2013, 01:45 PM   #9
DrDyna is offline DrDyna  United States
diyAudio Member
 
DrDyna's Avatar
 
Join Date: May 2007
Blog Entries: 3
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.
  Reply With Quote
Old 27th May 2013, 01:48 PM   #10
iand is offline iand  United Kingdom
diyAudio Member
 
Join Date: Feb 2007
Location: London
Quote:
Originally Posted by 5th element View Post
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)

Last edited by iand; 27th May 2013 at 01:55 PM.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
DAC lesson 101 question gychang Digital Line Level 0 14th January 2013 01:28 PM
I learned A lesson in Grounding today! Zero Cool Solid State 2 29th December 2007 11:06 AM
Sprint-Layout 4.0 lesson video and macros gev The Lounge 3 19th July 2006 05:55 PM
Learned a lesson today Ralph Tubes / Valves 9 18th December 2003 05:35 PM


New To Site? Need Help?

All times are GMT. The time now is 07:36 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2