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Acoustic Stealth Technology Finally Created
smitty777 writes "An idea for acoustic stealth technology proposed in 2008 was finally put into practice. The abstract describes taking advantage of the 'transformation acoustics and linear coordinate transformations that result in shells which are homogeneous, broadband, and compact. The required material parameters are highly anisotropic; however, we show that they are easily achievable in practice in metamaterials made of perforated plastic plates.' It is thought this technology might be useful for shielding ships from sonar or creating soundproof rooms."
The "stealthocopters" used in the bin Laden mission are way ahead of you!
Information theory is life. The rest is just the KL divergence.
This is the first I'm hearing of it.
Caffeine is my anti-drug!
Duranin - A NWN2 Roleplaying Persistent World
Finally, a cone of silence that actually works.
This does sound neat, but then I only understood the last sentence. It does make me wonder how applicable this would be to the "invisibility" cloak work?
Time to offend someone
The prototheoretical framework conceived by the authors involves the use of a minimization strategy with respect to the dampening properties of metamaterial plates, thus ensuring an optimized rendering of the phlogistonic metavariables in the form of an acoustic suppressing superstructure. The aim of this paper is twofold...
Please for the love of $DEITY make this a reality. Right now low frequencies are impossible to block so it's impossible to soundproof a room against those godamn fucking annoying boomcars.
When will I learn to stop clicking all those stupid links!
P.S. / Hint: I grew up in the 80's, so it's only mildly annoying to click those links.
I haven't heard anything about this.
The article says the materials are capable of acoustic cloaking in air. I assume from that wording that it does not (yet) work in water. But, assuming it could be modified to work underwater (and shielding a ship from sonar means it has to work in water, not in air) perforated plastic plates don't sound [pun intended] all that durable and I imagine they would induce a lot of drag on the hull.
...the future crusty old bastards are already drinking the Kool-Aid.
The big problem with modern stealth planes is that they may be invisible to radar, but they make a distinctive rumbling sound when they fly by. They way they deal with this now is they scientifically pinpoint where the sound is statistically likely to be heard, then they'll place a man on the ground to hold out his hand and say "Sounds like rain!"
"I like to lick butts!" by MobileTatsu-NJG (#32700246) (Score:5, Informative)
Please God, I hope you're referring to Rick-Rolls and not Goatse.cx links!
Learning HOW to think is more important than learning WHAT to think.
When you can silence a helicopter or a supersonic airplane, I'll be really interested.
-jcr
The only title of honor that a tyrant can grant is "Enemy of the State."
Just coat the blades and wings with hundreds of pounds of plastic with holes punched them... you'll never heard from the airplane or helicopter again.
I8-D
. . . . .
If a tree falls in the woods...
No, the goatse ones are real pain in the ass. ;-)
OK, I apologize for that one.
Lost at C:>. Found at C.
Cool. I'm dropping by the dollar store today to get me some plastic plates. At the next bbq, not only will there be no sounds, but food will be dripping in my guests' laps.
There are lots of reports from the American civil war of battles being heard ridiculous distances from where any fighting was actually going on, and in other cases being stumbled upon by people who nearly walked into the middle of them without hearing any fighting going on.
Seems to only apply in 2d and for a single acoustic transceiver. Static 3d might be achievable with some work, but I can't see how this is going to work for any kind of moving object or multiple transceivers, which is what would be required to make this useful outside of an enclosed room.
They can finally start working on silent bathroom stalls.
No, it is useful to have loud sounds warning all to stay away from the area
I think most of the comments (and the summary) are thinking around the wrong lines: If you could make something invisible, it's not because it doesn't EMIT light, but because it doesn't REFLECT it. Acoustic cloaking doesn't make something sound proof or silent. On the contrary, it makes it "transparent" to sound. It would be "invisible" to SONAR, I guess. If I've got this backwards, I apologize, but that's how understood the article.
Prov 9:8 Do not rebuke mockers or they will hate you; rebuke the wise and they will love you.
One possibility was that the waves of largest amplitude were infrasonic, and only after traveling some distance, could they generate sufficient harmonic scatter that the sound would be audible to human beings.
Try again, here. Beware of the wrath of the hams...
A house divided against itself cannot stand.
I'm afraid the trade-off between sound and smell will ruin any benefit... plastic with holes will simply not prevent you from getting the full olfactory experience of what your neighbor has been depositing!
This one is an "arch". What it does is create an (acoustic) illusion (think "virtual image") of a flat surface located behind it - at the same distance as the actual surface it's sitting on (assuming that surface is flat).
Result: Anything under the arch (either an object hiding there or a hole in the underlying surface) is not visible to the sonar, which instead sees the illusionary surface.
It's not an "invisibility cloak" because that would direct the sonar energy AROUND the object hiding under the arch, let it bounce off whatever is actually under it, and similarly redirect the sonar energy around the object again on its way to the detectors. (Problem with this: There will be an unavoidable delay, making whatever is behind the "cloak" seem farther away if you're timing the echoes - though not if you're just listening to their form. Metamaterial invisibility cloaks have the same problem: You'll see the object behind the cloak at the right distance, but if you ping it with a radar you get a longer return time.)
This thing is apparently using metamaterials to get the necessary delay to make the accoustic image appear at the right distance time-delay-wise, in addition to doing the wave-bending to make the sound take the correct paths.
Also: This is an early model and only works for sonar devices in a particluar halfplane. They claim they can make it work for sonar devices anywhere in the hemisphere "above" the device but that the design and layout for a fully dimensioned version is computationally much more difficult (and perhaps also harder to fabricate) so they haven't done it yet.
At least that's how I read TFA.
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
Now I get it. This works that same way as the Cone of Silence in Get Smart.
I find myself looking back on a life of denial. I wouldn't have that second helping of beans at dinner, or breakfast. Well, now my friends (grammar nazis- I don't leave you out), I can attract the flies of yesteryear without a fear of what you hear.
This technology has truly set me free. I am loosed upon the world! The rumble of the jets, which before seemed so quiet as I let out the sighing whimper of last night's taco bell, now is the only sound you hear as the smell fills the air without a whisper upon your ear.
In the distance you hear an ominous moo.
Finally, something that will keep my dog quiet and night. Probably will look fairly funny, though.
Vote monkeys into Congress. They are cheaper and more trustworthy.