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Science Technology

Acoustic Stealth Technology Finally Created 83

Posted by Soulskill
from the can-you-hear-me-now dept.
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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Acoustic Stealth Technology Finally Created

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

    • 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.
        • by Anonymous Coward

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

          Please slashdot, fix this problem already!

          • 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...".
    • by lennier1 (264730)

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

    • by youn (1516637)

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

    • by Anonymous Coward

      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 (unwittin

      • by Chris Burke (6130)

        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.

        • by x6060 (672364)
          They didnt call it the wobbly goblin for nothing. That thing was a brick with jet engines attached.
  • Odd... (Score:5, Funny)

    by Kirin Fenrir (1001780) on Monday June 27, 2011 @12:47PM (#36586624)
    This is the first I'm hearing of it.
  • by Anonymous Coward

    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?
  • Um... what? (Score:4, Funny)

    by Anonymous Coward on Monday June 27, 2011 @12:52PM (#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...

    • When I read:

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

      I thought, "Fast, quiet Internet?"

    • 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,

  • Soundproof rooms (Score:2, Insightful)

    by Anonymous Coward

    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.

  • by Anonymous Coward

    I haven't heard anything about this.

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

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

      Then again, so would huge holes from torpedoes.

    • by Genda (560240)

      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 t

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

  • by MobileTatsu-NJG (946591) on Monday June 27, 2011 @12:58PM (#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!"

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

    -jcr

    • 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.

      • by jcr (53032)

        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.... (Score:4, Informative)

      by Creepy (93888) on Monday June 27, 2011 @02:20PM (#36587802) Journal

      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).

  • If a tree falls in the woods...
  • 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.
  • 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.

  • 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.

  • 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

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

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