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Acoustic Stealth Technology Finally Created

Soulskill posted more than 3 years ago | from the can-you-hear-me-now dept.

Science 83

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."

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Interesting. (-1)

Anonymous Coward | more than 3 years ago | (#36586524)

Can it also be used to reduce low frequency windmill noise? [youtube.com]

Re:Interesting. (2)

Yvan256 (722131) | more than 3 years ago | (#36586776)

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.

Re:Interesting. (1)

chill (34294) | more than 3 years ago | (#36586860)

Please God, I hope you're referring to Rick-Rolls and not Goatse.cx links!

Re:Interesting. (2)

gstoddart (321705) | more than 3 years ago | (#36587196)

Please God, I hope you're referring to Rick-Rolls and not Goatse.cx links!

No, the goatse ones are real pain in the ass. ;-)

OK, I apologize for that one.

Bin Laden killing (1)

DriedClexler (814907) | more than 3 years ago | (#36586610)

The "stealthocopters" used in the bin Laden mission are way ahead of you!

Re:Bin Laden killing (1)

Bob the Super Hamste (1152367) | more than 3 years ago | (#36586680)

I think that is a different technology. I believe that some automakers experimented with similar technology for vehicle muffles a wile back, but basically they cancel out the noise.

Re:Bin Laden killing (1)

Bob the Super Hamste (1152367) | more than 3 years ago | (#36586754)

Re:Bin Laden killing (1)

Anonymous Coward | more than 3 years ago | (#36588598)

Damn slashdot doesn't let me click on fucking links!!!!!!!!!

Please slashdot, fix this problem already!

Re:Bin Laden killing (2)

cOldhandle (1555485) | more than 3 years ago | (#36591336)

This problem was introduced a few months back, and nobody really seems to care. I guess high-end website features like clicking links are pretty low priority in comparison to important Javascript/AJAX-y features like a notification on the bottom of the screen that perpetually informs us that something is "Working...".

Re:Bin Laden killing (1)

lennier1 (264730) | more than 3 years ago | (#36586730)

You're thinking of stuff like the technology to suppress the sonic boom of a rotor blade to reduce a copter's noise emissions,

Re:Bin Laden killing (1)

youn (1516637) | more than 3 years ago | (#36587056)

Obviously, that pre supposes they don't crash in a loud sound :)... but then again that would never happen in an operation like that :)

Re:Bin Laden killing (1)

Anonymous Coward | more than 3 years ago | (#36587730)

When the F117's were parked in Saudi Arabia before Desert Storm, sometimes the hangars would be found littered with bat corpses. Why? The bats' echolocation would fail against the shapes of the stealth fighters, so they'd blindly crash into them. (Source: Ben Rich, "Skunk Works". The chapter titled "Swatting at Mosquitoes", somewhere near the end of the chapter where they had sections written by pilots) So while this particular method of cloaking sound may be new, the concept has already been (unwittingly) applied.

Re:Bin Laden killing (1)

Chris Burke (6130) | more than 3 years ago | (#36588048)

Huh. And I thought the reason was that the bat's echolocation would give them a perfect image of the fighter, and they'd be thinking "Huh? They expect that thing to fly?!" and forget to change course.

Re:Bin Laden killing (1)

x6060 (672364) | more than 3 years ago | (#36588676)

They didnt call it the wobbly goblin for nothing. That thing was a brick with jet engines attached.

Re:Bin Laden killing (0)

Anonymous Coward | more than 3 years ago | (#36589584)

The "stealthocopters" used in the bin Laden mission are way ahead of you!

Except some guy in the village was tweeting about them tot the whole world some time before one of the helicopters crashed. Some stealth you got there, bro.

Odd... (4, Funny)

Kirin Fenrir (1001780) | more than 3 years ago | (#36586624)

This is the first I'm hearing of it.

Re:Odd... (1)

chemicaldave (1776600) | more than 3 years ago | (#36586728)

Hearing what? I can't hear anything.

Re:Odd... (1)

tom17 (659054) | more than 3 years ago | (#36586832)

I SAID 'WHAT DID YOU SAY?'

Re:Odd... (1)

CastrTroy (595695) | more than 3 years ago | (#36587610)

I said, "You have a gingerbread man in your ear!".

Re:Odd... (1)

realityimpaired (1668397) | more than 3 years ago | (#36586828)

Never watched Get Smart, did you?

Re:Odd... (1)

somersault (912633) | more than 3 years ago | (#36586974)

Did you just hear a kind of whooshing sound?

Re:Odd... (2)

Pope (17780) | more than 3 years ago | (#36587072)

Would you believe 3 whooshes and a duuuh?

Re:Odd... (1)

SilentStaid (1474575) | more than 3 years ago | (#36587248)

He would have, but it's already been implemented!

Re:Odd... (1)

Lashat (1041424) | more than 3 years ago | (#36587278)

I must have missed it by .. that much.

Re:Odd... (1)

Genda (560240) | more than 3 years ago | (#36587384)

I said "MAX, Raise the cone of silence!!!"

"WHAT?!!! I can't hear you!!!

Re:Odd... (1)

Skater (41976) | more than 3 years ago | (#36587878)

"Max, I think there's something wrong with the Cone of Silence!"

"Never mind that, 99, there's something wrong with the Cone of Silence!"

Okay, so that was actually from the Get Smart, Again movie. I always felt like that movie stayed pretty true to the Get Smart theme...unlike a certain other movie that was made with the Get Smart name.

Re:Odd... (1)

cyberfin (1454265) | more than 3 years ago | (#36594582)

Dear Sir, I think you mean the "shushcopter".

Get Smart! (1)

Anonymous Coward | more than 3 years ago | (#36586630)

Finally, a cone of silence that actually works.

Re:Get Smart! (1)

White Flame (1074973) | more than 3 years ago | (#36588226)

What?

And I only understood the last sentence. (1)

Bob the Super Hamste (1152367) | more than 3 years ago | (#36586640)

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?

Re:And I only understood the last sentence. (0)

Anonymous Coward | more than 3 years ago | (#36586780)

basically right now... its only possible with highly accurately built materials that aren't easily massed produced (likely), and are probably really expensive for home sound proofing compared to foam, for now at least. So it will only have limited uses, and are likely really expensive at this, like studio sound proofing, or military uses(both of which were listed),

Um... what? (4, Funny)

Anonymous Coward | more than 3 years ago | (#36586708)

'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.'

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...

Re:Um... what? (0)

Anonymous Coward | more than 3 years ago | (#36587602)

That's the style in which these things are supposed to be written.
Google "abstract" and "academic prose".

Re:Um... what? (1)

StormReaver (59959) | more than 3 years ago | (#36587638)

When I read:

...that result in shells which are homogeneous, broadband, and compact...

I thought, "Fast, quiet Internet?"

Not really an accoustic "invisibility cloak". (1)

Ungrounded Lightning (62228) | more than 3 years ago | (#36588294)

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.

Soundproof rooms (2, Insightful)

Anonymous Coward | more than 3 years ago | (#36586752)

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.

Re:Soundproof rooms (0)

Anonymous Coward | more than 3 years ago | (#36587782)

when you are in the boomcar it is fun. ok

Re:Soundproof rooms (0)

Anonymous Coward | more than 3 years ago | (#36587800)

Maybe, if you're fucking deaf.

I doubt it (1)

Anonymous Coward | more than 3 years ago | (#36586784)

I haven't heard anything about this.

Re:I doubt it (1)

SilentStaid (1474575) | more than 3 years ago | (#36587268)

I guess we can forgive you for not "hearing" the first time this joke was used in this article, given the context.

submarine use? (1)

treeves (963993) | more than 3 years ago | (#36586788)

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.

Re:submarine use? (2)

Mister Whirly (964219) | more than 3 years ago | (#36586890)

I imagine they would induce a lot of drag on the hull

Then again, so would huge holes from torpedoes.

Re:submarine use? (0)

Anonymous Coward | more than 3 years ago | (#36587146)

Off-topic but those torpedoes holes are normally closed... They have something called muzzle doors....

http://en.wikipedia.org/wiki/File:Submarine_torpedo_tube.svg

Re:submarine use? (3, Funny)

Abstrackt (609015) | more than 3 years ago | (#36587216)

I think Mister Whirly was referring to the torpedo holes the enemy installs in your sub.

Re:submarine use? (1)

cyberstealth1024 (860459) | more than 3 years ago | (#36589116)

the torpedo holes the enemy installs in your sub

+1 Funny (sorry, I don't have any mod points)

Re:submarine use? (1)

RivenAleem (1590553) | more than 3 years ago | (#36594920)

That's okay, I do ..... Dammit.

Re:submarine use? (1)

nschubach (922175) | more than 3 years ago | (#36587272)

I think he means the hole created from a torpedo hitting the ship not using said "cloaking."

Re:submarine use? (0)

Anonymous Coward | more than 3 years ago | (#36587120)

I think this would be put inside the hull so that the mechanical and human noises would not be able to be heard by enemy sonar. Our ships and props are pretty quite, but it only takes one sneeze.

Re:submarine use? (1)

Talderas (1212466) | more than 3 years ago | (#36587648)

There are two types of sonar. Active and passive. Assuming the material blocks all sound passing through it, it's a very useful advance for protecting a vessel against passive sonar since it can be installed inside the hull and block sounds originating from within your vessel.

Re:submarine use? (1)

treeves (963993) | more than 3 years ago | (#36588998)

That makes sense, but calling it "shielding from sonar" makes it sound like that was not what was meant. Of course the sounds from inside the hull that are going to give the boat away to passive sonar are sounds directly coupled to the hull, like dropping a wrench in the bilge , or coming down a ladder (which is bolted to the hull) noisily. Or pumps not adequately isolated from the hull, etc.

Re:submarine use? (1)

Genda (560240) | more than 3 years ago | (#36587508)

Not necessarily. Look at the dimples on a golf ball or the irregular surface of whales, and what you find are structures that create small rotating eddies all over the surface of the object, acting like soft ball bearing and significantly reducing drag. So, if you shape the sound reduction holes right, you can actually decrease drag dramatically. As well, if you choose the plastic carefully (laminated sheets of polycarbonate, and perhaps a kevlar or carbon fiber fabric) you should have something stronger than metal, more durable, and able to take the worst possible beating with impunity.

Re:submarine use? (1)

Anonymous Coward | more than 3 years ago | (#36587726)

also, it will mine valuable metals from the ocean, de-acidify surrounding water, and naturally sequester 10^15 X its mass in carbon dioxide.

Re:submarine use? (1)

Ungrounded Lightning (62228) | more than 3 years ago | (#36589072)

I see no reason the "holes" actually have to be all the way through. A flexible diaphragm covering each one (easily built by sheathing the whole plate in a film) would deflect the water flow while passing the sound about as well as an open hole. For "DC" the surface is continuous. For sonar it's full of holes.

Summary of the Article... (3, Funny)

MobileTatsu-NJG (946591) | more than 3 years ago | (#36586800)

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!"

Science of the scientist, art of the engineer. (0)

Anonymous Coward | more than 3 years ago | (#36586862)

It works by using stacked sheets of plastic with regular arrays of holes through them. The exact size and placement of the holes on each sheet, and the spacing between the sheets, has a predictable effect on incoming sound waves.

Now what does that do to the fluid dynamics of a submarine, or an airplane? Remember engineering is the art of managing sometimes conflicting goals.

Yeah! (0)

Anonymous Coward | more than 3 years ago | (#36586884)

Ninja PJ's! No more getting caught having a midnight bowl of ice cream!

Okay, but.... (1)

jcr (53032) | more than 3 years ago | (#36586896)

When you can silence a helicopter or a supersonic airplane, I'll be really interested.

-jcr

FTA (1)

Kamiza Ikioi (893310) | more than 3 years ago | (#36587036)

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.

Re:FTA (1)

jcr (53032) | more than 3 years ago | (#36587118)

Ok, I'll be more specific: when you can silence a helicopter or supersonic airplane while it's flying, I'll be interested.

-jcr

Re:Okay, but.... (3, Informative)

Creepy (93888) | more than 3 years ago | (#36587802)

Actually, aerodynamics technology can make a supersonic airplane signature (aka "boom") almost silent - the military and NASA has been investing in that for years.

For instance, from NASA's website [nasa.gov] :

Ltpinter: Hi Ed. I hope NASA is keeping you busy on really cool stuff. I would like to know if sonic booms can be reduced to a low rumble?

Ed.: Yes, we can make sonic booms that are very quiet, and can't be heard over normal conversation. It sometimes sounds like distant thunder. And referring to my last comment sometimes you can make the boom totally quiet if the aircraft is slow enough or high enough in altitude.

I know Eurocopter is working on a quiet helicopter, but I couldn't find the one I know about (nor can I talk about it, because they are a customer I'm working with). It may be the same technology as I was able to find, [eurocopter.com] but I'm not sure.

This technology has a different application - it bends sound around the object it surrounds, so sonically it appears to not be there. Being able to bend waves of different kinds around objects has fundamental uses - for instance, if you can bend radiation around a spaceship, you eliminate one of the problems with the theoretical Alcubierre drive (though I would say the theory existed before he wrote about it, as people in my physics class discussed it amongst other "further than light" ideas before 1994 - the two that we couldn't debunk were time bubbles and one that is difficult to describe, but I'd call it uncertainty tunneling).

Let me be the first to say... (1)

DaftDev (1864598) | more than 3 years ago | (#36587084)

. . . . .

Krakatoa sound waves disappeared (0)

Anonymous Coward | more than 3 years ago | (#36587114)

There was once a verified - and bizarre - sound stealth phenomena in real word.

In 1883, Krakatoa erupted in one of the loudest volcanic eruptions in the modern world. It was heard over a thousand miles away in Australia.

In a bizarre twist some islands much closer to the blast never heard it. Why the sound of this eruption skipped over nearby areas and yet the sound was clearly heard by other far distant places has never been understood.

Re:Krakatoa sound waves disappeared (1)

black soap (2201626) | more than 3 years ago | (#36587262)

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.

Re:Krakatoa sound waves disappeared (1)

Genda (560240) | more than 3 years ago | (#36587582)

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.

Finally a solution to the age-old question... (1)

coinreturn (617535) | more than 3 years ago | (#36587178)

If a tree falls in the woods...

Re:Finally a solution to the age-old question... (1)

Mindcontrolled (1388007) | more than 3 years ago | (#36587778)

Being purely acoustic, this still doesn't solve the "light in the refrigerator" question, though.

Re:Finally a solution to the age-old question... (2)

coinreturn (617535) | more than 3 years ago | (#36587956)

I put my kid in the refrigerator to solve that question. Unfortunately, he became a schrodinger's cat.

Re:Finally a solution to the age-old question... (1)

Mindcontrolled (1388007) | more than 3 years ago | (#36588042)

Gotta collapse that wave function. Quarter pound of C4 will do.

Perforated plastic plates... (1)

coinreturn (617535) | more than 3 years ago | (#36587206)

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.

wonderful! (0)

Anonymous Coward | more than 3 years ago | (#36587324)

They can finally start working on silent bathroom stalls.

Re:wonderful! (1)

clampolo (1159617) | more than 3 years ago | (#36587464)

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

Re:wonderful! (1)

Genda (560240) | more than 3 years ago | (#36587630)

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!

fagget's (0)

Kerstyun (832278) | more than 3 years ago | (#36587414)

transformation acoustics and linear coordinate transformations that result in shells which are homogeneous

We ain't having none of them in this man's man's ayer fowse, no sirrie.

Seems very limited (1)

David Frankenstein (21337) | more than 3 years ago | (#36587434)

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.

Power Line Communication... (0)

ForeverOrangeCat (1430461) | more than 3 years ago | (#36587488)

When I first seriously started thinking of smart grid applications back in 2002... this is what I thought they would be using...

http://en.wikipedia.org/wiki/Power_line_communication [wikipedia.org]

Why implement a step back in tech when they could do BPL? Seems like it is drastically more realistic(see cheaper) in implementation than a wireless network.

Re:Power Line Communication... (1)

pedestrian crossing (802349) | more than 3 years ago | (#36587606)

Try again, here [slashdot.org] . Beware of the wrath of the hams...

Not stealth? (1)

Bob-taro (996889) | more than 3 years ago | (#36587490)

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.

April's fool? (0)

Anonymous Coward | more than 3 years ago | (#36587604)

After reading the summary twice, I caught myself looking at the calendar to see if it was April 1st... Reminds me of GURPS' "invention" on Supers, where you could built a Deteronic Frombotzer just with the stuff on your gloves compartment, or an Interphasic Fromblitzer with what you had on your pocket.

Jokes aside what about (0)

Anonymous Coward | more than 3 years ago | (#36587966)

what about using this for motorcycle helmets. Too bulky maybe? Could be cool to selectively damp the motorcycle sound and allow the traffic sounds through.

Cone of Silence Explained (1)

whatnever (1028390) | more than 3 years ago | (#36588514)

Now I get it. This works that same way as the Cone of Silence in Get Smart.

Its about time (0)

Anonymous Coward | more than 3 years ago | (#36589762)

"or creating soundproof rooms."

This can't happen soon enough.

Beans are your friend (1)

user flynn (236683) | more than 3 years ago | (#36591344)

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.

Quiet dog (1)

bryan1945 (301828) | more than 3 years ago | (#36594298)

Finally, something that will keep my dog quiet and night. Probably will look fairly funny, though.

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