Schneier on Security
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February 18, 2008
Story of a sonic blaster:
Here's how it works: Inferno uses four frequencies spread out over 2 to 5 kHz. The idea behind it is that unlike a regular siren, these particular frequencies have a uniquely disturbing effect on people (and presumably cats, dogs and any other living thing). At 123 dB, it's loud, but not significantly louder than any other alarm system. The advantage, according to Dr. Goldman, is the combination of frequencies. The human ear just doesn't like it. I agree, I really didn't like it.
Note to the TSA: Dr. Goldman has had no problems bringing this thing onto airplanes.
Posted on February 18, 2008 at 6:16 AM
• 27 Comments
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Soon, possession of earmuffs and sunglasses will be prohibited to ensure this device's effectiveness.
I mean, really, as a defense for Russian nuclear weapons storage?
As for home defense, it might be effective as long as it is not used widespread and the burglars are not prepared for something like this. This fits in nicely with the other deterrents like smoke generators.
Once burglars are prepared for such things, they will bring cheap and easy countermeasures, like good quality earplugs, or maybe just a bottle of PU foam.
Thanks, Bruce, for your notice to the TSA. In the future, we will not only have to throw away our water bottles, but also our iPods.
Any musician can tell you that combining some frequencies can be disturbing, and 4 carefully-chosen frequencies at a high volume probably can be really bad.
The fire alarms here at work, and the "case open" alarm on our AED boxes both have a two-tone piezo alarm. It's not terribly loud, but the two tones beat against one another and I can actually feel a physical beat inside my head when it goes off. It's not pleasant and you just want to shut it off or get away from it, which is of course the desired effect.
I wonder if wearing noise-canceling headphones would effectively protect someone against this device.
Some years ago, a burglar in Berlin robbed an art exhibit blind. He put a small box over the siren and light taht was attached to the wall of the house, filled the box with PU foam, openend the door with a crowbar, went in, packed a few pictures, and was away before the police arrived on the scene (they, of course, had registered the alarm). Since nothing was hear, noone in the neighborhood was suspicious.
didn't MythBusters do an episode on the affects of low frequency noises on the human body? I seem to remember speakers and an adult diaper involved and that it was busted.
Noise canceling headsets work on the lower frequencies (
note (in German) to human rights and sound weapons:
"Akustische Waffe oder harmlose Teenagerabwehr?
Das zur Vertreibung von Jugendlichen angebotene Gerät Mosquito verstößt möglicherweise gegen die Europäische Menschenrechtskonvention"
@bear: The mythbusters tested the "brown note" myth, that an inaudibly low-frequency sound could make you lose your bowels (and that such a device was supposedly in use by the US army). Despite playing a full sweep at up to 160 dB, there was no effect on the test subject (who was wearing protective headphones). See http://en.wikipedia.org/wiki/...
@grs1969: Noise canceling headphones give you an additional ~15 dB in the low frequency range, on top of the protection from the headphones themselves. Starting from 120 dB, that still leaves plenty room for discomfort. (15 dB at
To add to Reperdor's heise article reference, the BBC reports on a a campaign in the UK to ban the "mosquito" teen repellant sound systems:
There is a flip side to those high frequency sounds. They are used for "teens only" ringtones so adults can hear them.
By the way, the ability to hear those high frequencies is not limited to young folks. Some older adults, myself included, can hear those frequencies.
The sonic weapon, apparently, would be of little use against people with significant hearing impairments.
The sonic weapon does remind me of the concept that bagpipes served/serve as battlefield psychological weapon.
@J.D.: I watched Braveheart last night for the first time in years. I loved the scene during the battle at Stirling, after the first volley of arrows has fallen on the scottish troops, they all shoot back to their feet and start yelling and screaming while the bagpipes play happy jigs.
2 - 5kHz isn't particularly high or low frequency for the human ear. Most of that range is on the piano keyboard: "C7 is 2kHz, and key 88 is just over 4kHz. 2kHz is also typically accepted as the frequency at which the average human ear is most sensitive, per the A-weighting scale. A chord of these pitches would sound pretty high and probably be really unpleasant, though. It seems to me that drug-store ear plugs would help damp this range by 20dB or so. I don't know if that would make it any more tolerable, but hopefully it would reduce hearing damage.
If I understand active noise cancellation correctly. They work best with constant sounds, like jet liner noise.
I saw them using this on "Future Weapons". It seems the sonic gun is quite effective. Though they didn't show how effective it was with sound dampening, IE ear plugs and muffs.
Perhaps we'll have to outlaw the deaf.
At a certain volume it does not matter how bad your hearing is, you will feel it.
Having been to some very loud concerts, it does not matter what ear protection you wear, the pain is always there.
Can you say "Skinny Puppy concert" boys and girls? I knew you could!
I was delighted by the Mythbusters that built complicated suits of foam and carpeting trying to defeat sonic motion-detector devices, to no avail.
At the end of the segment one of their researchers decided, apparently on a whim, to try simply holding a big bedsheet up between herself and the sensor, to soak up the sound waves. It worked magnificently, and she was able to move easily through the room without triggering the detector...
The other way that worked was to cross the room very, very, very slowly...
Unless they are operating at the specific resonant frequencies of certain vital organs, this is basically trumped up research in normal sonic annoyance. As mentioned above, this is the range within which (similar to the telephone range) the human ear has evolved to be the most sensitive, due to the pitch and modulations of the human voice. Any sound at or near the threshold of pain (130dB) in this range is going to be unbearable, and may cause permanent hearing damage. I guess they are seeking to enhance the effect using cacophony because it produces erratic harmonics in a more efficient manner.
We've known this forever. Hell, just crank up some old Dead Kennedys and listen to East Bay Ray. He invented this weapon decades ago, with neither funding nor a specific deterrent purpose.
"vertigo, nausea, and _pain in the chest_."
What happens if you have a heart condition? You die?
Other than that I don't think it would be as effective as you might first think. Lady says at the end that covering her ears with her hands helped a lot - what is the first thing you do when you hear a really offensive noise? Still, if your hands are covering your ears you can't effectively combat someone.
Unless you got some freaky elbow kung-fu...
I could see some real uses for this. Consider the psychological effects of sirens and strobe lights. People go into full blown panic reactions, especially when caught by surprise.
The biggest advantage (problem?) is that it's going to be more effective on the unprepared layperson than it will be on the prepared, enraged, etc.
In other words -- crowd control weapon to chase off the harmless before using the water cannon, etc.
I hope this thing comes with a remote control to turn this beast off. Imagine you sleeping, that "thing" went off, false alarm and no remote... haha.
So - what are the four frequencies?
So we finally have something to use against the people who shout into their cell phones in public!
Anyone know where I can get a recording of this ? I know a few people who need a new Windows startup sound.
@David: I was also looking for a sound file of Inferno a while ago...Anyway you can read more about sonic-barrier / download sound file at www.odonod.com/inferno
Having the pleasure of having a similar device used on me by criminals in the Dominican Republic. I think these devices offer wonderful chances for abuse. Combine a see through walls device with a targetted wall penetrating tone at 150 db, you have a perfect way to drive your neighbor crazy while everytime he tries to explain what he is going through everyone thinks his crazy and when he goes crazy everyone can say "told you so!" I think there will be tragedies on both sides with this technology.
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