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Pinholes and Plastic Wrap Make Solid Walls "Transparent" To Sound

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  • by Anonymous Coward on Thursday June 20, 2013 @04:02PM (#44064201)

    I thought we were trying to figure out how to keep sound from coming through the wall, not help it!

    • New NSA-Approved Building Code
    • by AK Marc (707885)
      People building a nursery may want something like this, or use in prisons to reduce privacy without removing all of it (not that they can't just put a mic on one side and a speaker on the other, as is done today).
      • by hedwards (940851)

        Doubtful, you'd have to replace the entire wall when you no longer wanted to hear through it. What's more, it would work both ways, which means that not only would you hear your baby, but your baby would hear whatever nasty stuff you're doing next door.

        A baby monitor OTOH, can be carried from room to room as need be, and can only be heard in one direction. The main disadvantage would be the batteries or the possibility of eaves dropping.

      • by xenobyte (446878)

        ..., or use in prisons to reduce privacy without removing all of it (not that they can't just put a mic on one side and a speaker on the other, as is done today).

        Is reducing privacy as much as possible part of the punishment?

        I thought prisons were about keeping criminals off the street in a manner able to handle all kinds of people, from the quiet types to the ultra violent and/or gangbanger types? - I don't see how removing privacy and making all noises travel easily helps this.

        An ideal prison for lifers without parole (and possible also death row) would be small individual cells with a shower and toilet, with or without a windows. The inmate will spend all his/he

        • by Anonymous Coward

          I thought prisons were about keeping criminals off the street in a manner able to handle all kinds of people, from the quiet types to the ultra violent and/or gangbanger types?

          No, that is a gross oversimplification.

          When it comes to handling criminals there are three major things to weight against each other: Rehabilitation, deterration, protection and revenge.

          If you intend to rehabilitate a criminal then imprisonment can serve as a punishment that will "teach" the criminal that it shouldn't commit crimes. It isn't very efficient since the imprisonment comes so late after the crime that it doesn't have a psychological impact on the prisoner, only a conscious one. It only works as

          • by JeanCroix (99825)

            When it comes to handling criminals there are three major things to weight against each other: Rehabilitation, deterration, protection and revenge.

            By my count, that's four major things, Cardinal Ximinez.

        • by AK Marc (707885)
          What's the point of prison? Punishment, deterrent, revenge, other?
    • by WillgasM (1646719) on Thursday June 20, 2013 @04:18PM (#44064387) Homepage
      If only there was an article enumerating possible applications of this technology.
    • by JustinOpinion (1246824) on Thursday June 20, 2013 @04:39PM (#44064627)
      Well, TFA [insidescience.org] suggests:

      The research has potential uses in creating security barriers that permit voice communication to pass through, and in developing types of sound-based microscopes that could find application in research laboratories and medical practice.

      The scientific paper [aps.org] further notes:

      Such a high concentration of acoustic energy into a small hole of radius enables sensitive detection of acoustic signals with subwavelength resolution ... the present work not only opens the way to the efficient realization of [near-field acoustics] in fluid ultrasonics and underwater acoustics, but also to the analogous realization in solid-state ultrasonics.

      More broadly, results obtained for one kind of wave behavior often have implications for other kinds. I.e.: results in controlling acoustic waves sometimes have implications in controlling/sensing light-fields, or radio waves, or even more esoteric things like electron beams or neutron beams (which are also regulated by wave equations).

    • by Jamu (852752)
      They should have talked to whoever designed my flat.
  • by Anonymous Coward on Thursday June 20, 2013 @04:02PM (#44064205)

    Fantastic, now we have walls that sound like they aren't even there. What's next, ovens that are just as hot on the outside as they are on the inside?

    • by calzones (890942)

      brilliant

    • Hey man, not all research is immediately useful, but can lead to other things. One day, this research might lead to better speakers that take up a whole wall. Or better acoustics in concert halls. Maybe even walls that allow not just sound to pass through, but people and light and everything else as well. They might call that last one "there is no wall here." How crazy would that be?
      • ...but people and light and everything else as well.

        Maybe it's just me, but I don't think thats a wall anymore.

      • by tlhIngan (30335)

        One day, this research might lead to better speakers that take up a whole wall.

        Or more practically, the ability to have a nice surround sound system at home without speakers and wires popping out of the wall. No more compromising the audio because your significant other wanted to put something where the speaker is.

        Or the ability to have huge ass speakers in the walls without disrupting the aesthetics of the room. You can bet more than one person was subject to buying Bose purely because their significant ot

      • by unitron (5733)

        ... Maybe even walls that allow not just sound to pass through, but people and light and everything else as well. They might call that last one "there is no wall here." How crazy would that be?

        The theater already has one of those, they call it the fourth wall.

    • by Kingkaid (2751527)
      Not ovens silly. It will mean when you hear noise from the apartment next door you can say "Those are well engineer walls".
  • And in other news... (Score:3, Informative)

    by RdeCourtney (2034578) on Thursday June 20, 2013 @04:04PM (#44064231) Homepage
    Researchers find that by putting a glass to a wall, helps sound travel through rigid surfaces as well.
    • by lxs (131946) on Thursday June 20, 2013 @04:16PM (#44064363)

      It's like that very old joke: Earlier today researchers announced the invention of a device that makes it possible to see through brick walls. They have named this contraption a "window."

      • by AK Marc (707885)
        So this one, they'll name "passive speaker"? It's nothing more than a microphone and passive speaker in one, one side of the plastic wrap providing each of the two functions.
  • by Anonymous Coward

    This technology is going to be widely used by builders of apartments and condominium complexes. They are constantly striving to build thinner and thinner walls. This is going to revolutionize the industry.

  • by sl4shd0rk (755837) on Thursday June 20, 2013 @04:06PM (#44064257)

    It would be nice to use plastic wrap to make walls impenetrable by sounds of penetration.

    • by judoguy (534886) on Thursday June 20, 2013 @04:18PM (#44064393) Homepage

      There is vinyl sheeting for just this purpose.

      Mass Loaded Vinyl [acousticalsolutions.com] is a sheet of heavy vinyl that is loosely hung to absorb sound. Usually hung in the wall between the drywall layers for appearance sake, would still work just fine tacked on the outside of the wall separating you from your noisy neighbors.

      Of course, sound will travel through the ceiling and floor as well.

      • by Anonymous Coward

        Wow, expensive, and for something that weighs a crapload (1 pound per square foot, and the smallest/cheapest roll covers 68 square feet). You wouldn't easily be able to "hang" this or "tack it on" to the outside of an existing wall. Dropping this stuff down into an existing wall is usually not possible given the amount of reconstruction that would be warranted (e.g. having to cut large slits in the floor or roof (many MDUs lack crawlspace) or possibly the wall itself). This stuff is, as you state initial

        • by hubie (108345)
          Why do you think the rest of the world is quiet? I've stayed in some pretty noisy places outside of the US.
        • A lot of cultures have different noise standards than traditional US standards.

          I have a friend who regularly is run out of her house by noise so loud you can hear it inside wearing gun headsets and the county police can't legally do anything.

          So she comes to my house inside the city limits where we have noise limits after midnight.

    • by macraig (621737)

      I second that wish!

      (I'm not an apartment dweller, but... I "own" a 2-story townhouse with a 2-story shared wall.)

      • by h4rr4r (612664)

        How is that any different than an apartment? Because you own a door to the outside?

        • by Anonymous Coward

          The delineation is because:

          1) They share a single wall with their neighbours (while most apartments, barring the end units, share 2 or more walls -- not including floors/ceiling if multi-levelled),
          2) They have nobody living above them or below them,
          3) Townhouses are usually larger (in square footage offered), particularly if it's a duplex unit -- these are usually the equivalent of two small houses put together sharing a single wall.

          • by macraig (621737)

            A single common two-story wall is MUCH worse than any two single-story walls. You've never lived in that situation, or you'd already know why. All the impacts, vibration and resonance from the entire linked second floor subfloor is funneled into that wall, which acts like a giant subwoofer in response.

            Actually I got off easy because I'm on the end of a four-dwelling structure: were I living in one of the two central dwellings, I'd have TWO shared two-story walls instead of just one.

        • by macraig (621737)

          Read my reply to the AC that also replied to you.

  • by icebike (68054) on Thursday June 20, 2013 @04:14PM (#44064341)

    Ok, build a bunch of drum heads into a wall and notice they act just like, well, drum heads.
    Brilliant. An acoustic diaphragm. [wikipedia.org]

    Can't think of a single use for this other than eves dropping where no electronics were allowed.

    • by jeffmeden (135043) on Thursday June 20, 2013 @04:22PM (#44064439) Homepage Journal

      Ok, build a bunch of drum heads into a wall and notice they act just like, well, drum heads.
      Brilliant. An acoustic diaphragm. [wikipedia.org]

      Can't think of a single use for this other than eves dropping where no electronics were allowed.

      NSA Jokes, apartment sex jokes, etc. aside this is apparently a potential way to increase the precision of ultrasound scanning for medical diagnosis. As medical imaging is being used extensively to diagnose early cancer (among many other things), advances like this could have really profound effects on healthcare.

      • Re: (Score:3, Interesting)

        by archshade (1276436)

        There's also a use in controlled/clean rooms. You can already get some something similar, there called Talk-Throughs [terrauniversal.com] (not affiliated, just top google hit).

        I am not sure if this technology has a benefit over the existing solution, but it may. Maybe just because it looks cool. There is also a section at the bottom of TFA that gives over uses.

    • by sir-gold (949031) on Thursday June 20, 2013 @04:23PM (#44064453)

      The important part isn't the membrane, it's the fact that the hole was smaller than the wavelength of the sound, which,according to conventional theories about wave propagation, should not have allowed any sound though, membrane or no membrane

      • by mdielmann (514750)

        So the theory is incorrect (more likely incomplete). That's good news for science - something else to think about for a few years!

        I'd be unsurprised to learn that the reasons are due to air being a fluid, the holes being spread out over a large surface (similar to the enhanced resolution of a telescope array), and the holes being large enough for air to flow through. Compression waves in the air pass through the holes, propagate on the other side, and are amplified by the membrane. I guess I could read t

      • by Anonymous Coward

        The important part isn't the membrane, it's the fact that the hole was smaller than the wavelength of the sound, which,according to conventional theories about wave propagation, should not have allowed any sound though, membrane or no membrane

        This works because the sheet converts sound into pressure waves... like y'know... a drum. It absolutely is the conventional theory as to what happens when you have small holes in an acoustical partition (with or without a membrane). See also: the acoustic baffles for

    • by Hatta (162192)

      Can't think of a single use for this other than eves dropping where no electronics were allowed.

      It would be nice to be able to turn the stereo on in the living room and hear it from the kitchen without cranking the volume up to eleven.

    • by jbengt (874751)

      Can't think of a single use for this other than eves dropping where no electronics were allowed.

      Actually, this might be useful for the design of sound attenuators. Letting the sound out of a space (say an HVAC duct) into another in order to absorb it with heavy weight mineral wool or the like could be a common application. TFA didn't go into any details, though, so I don't know if this could be any improvement over what is already done. (It sure sounds similar to how a lot of silencer walls are already

  • by Doug Otto (2821601) on Thursday June 20, 2013 @04:14PM (#44064343)
    I think the bathroom across from my office has this "technology" already.
  • Finally (Score:5, Funny)

    by ArcadeMan (2766669) on Thursday June 20, 2013 @04:17PM (#44064383)

    Spying gear for Bond. Amish Bond.

  • Because those guys have making walls (and floors and ceilings) transparent to sound completely mastered.
  • by niftymitch (1625721) on Thursday June 20, 2013 @04:21PM (#44064435)
    Is this trick bidirectional?

    If it is mono-directional it has application as sound proofing.

    If it is bidirectional then the listener can be heard doing what listeners do as well as the "target".

    If regions could be made "transparent" then 3D audio precision might be possible.

    Interesting.... but I am not going to dig holes in my walls.

  • I would expect that these walls are rather one way with the transmission of sound, as in a one way mirror.

    But, by alternating the side of the holes that are covered with plastic wrap, we could then make these walls truly two way with regards to sound transmission.

  • Slashdot has research from Japan flagged for some reason? I haven't noticed any other countries represented in flag form, for instance, the south korean flag too.

    A team of Japanese and South Korean researchers has devised a means of making solid walls virtually transparent to sound.

    • by dido (9125)

      It's strange that articles here only seem to have one of those icons with them nowadays. I could remember a time when there were three or sometimes even four icons relevant to a story when you opened it up (e.g. Google and Microsoft icons for stories involving both companies). Wonder why that stopped.

  • Now you will have to pay extra to SEE the band.
  • The sound goes through. Oh this is such a break through! No one ever thought of this! No one would ever think that a hole might alter the optical properties as well? Well it does! You can see through a wall with holes in it! It's amazing!

    • by Zynder (2773551)
      The way you say that, you sound British. If so, you've got the usage wrong for Americans. A pit is a pit, not a hole. A pit has a bottom, a hole doesn't even though we often say things like a hole in the ground. That's a colloquial thing though. This is a scientific article so in the scientific sense, a pit has a bottom and a hole goes all the way through. You put a pit in the wall like a golf ball has and stretch plastic over it. What they have reinvented is a wall covered in musical drums.
  • by queazocotal (915608) on Thursday June 20, 2013 @04:40PM (#44064645)

    The 'walls' were thin sheets of metal - yes - this is an interesting breakthrough, but will not help much for thick walls.
    The effect is strongly frequency dependant, and relies on tuned membranes.
    It will not work for signals such as voice.

    Or at least - it will not work as well as it would for tuned signals.
    It is unclear if you can get a useful effect with a large number (say 50) of tuned membranes covering the voice band.
    You can perhaps also do interesting novel things with tuning, if this is possible.
    You can have a 'transparent' wall - that mutes certain tones - for example if you want to notch out a train whistle that goes past every day.

    Audio prisms are another application that springs to mind.

    • by jbengt (874751)

      The effect is strongly frequency dependant, and relies on tuned membranes

      I was wondering about that. TFA left that out. If so, then it would more useful as a sort of filter, more than a device to reduce reverberation or increase transmission in general.

  • by Anonymous Coward

    Actually, I'd be much more interested in how to make solid walls transparent to the frequencies used in 802.11b/g/n/ac transmission, particularly the higher frequencies that are more easily stopped by walls.

    For example, if I drove a very long nail through a wall, could it serve as an antenna that would help propagate wireless from one side to the other?

    • by qwijibo (101731)

      If the nail is made of copper, insulated, run through the wall and connected to the external antenna port on the wireless device?

  • Researchers have devised a means of making sound transmit easily through rigid surfaces, including walls. The process relies on creating large holes in a wall. Researchers have discovered the large holes do not require that either side need be covered with plastic wrap, thus making the process more environmentally friendly.
  • A pinhole and plastic wrap also make it transparent to visual frequencies!

    -100: Ten thousand people did that joke already.

  • Apartment complexes had this technology in their walls (and ceilings and floors) years ago.
  • by bdwoolman (561635) on Thursday June 20, 2013 @05:02PM (#44064797) Homepage
    Every motel I ever checked into has had these walls installed.
  • My apartment has had walls that transmit sound since it was built in the 1950s.
  • How to mess with/prank the blind.

  • So to get sound to go through walls what you do is remove a bunch of pieces of the wall. This is essentially a window, but instead of having it all in one chunk you spread out the area. BRILLIANT!!!
  • If you can quickly cycle the pinholes open and closed then you could put a speaker on the other side and dynamically control where the sound apparently originates.

  • But, wouldn't it just be easier to put speakers in the other room and get on with your life?

    Well, I guess maybe if you were in the room next door, and wanted to hear what was going on without the occupants knowing, you could use this method.

    I get it now. Perfect for NSA spying ops.

  • More info... (Score:4, Interesting)

    by slew (2918) on Thursday June 20, 2013 @06:59PM (#44065743)

    Some complementary work done at UT-austin [blogspot.com]

    Instead of a membrane matching the impedence of a "meta-material" made by punching regularly spaces in a wall [hokudai.ac.jp] (kind of like a meta-material drum), the UT-austin work describe holes made with a "meta-material" approach. Basically a hole with some transverse tubes cut a regular intervals to create resonances that change the effective impedance parameters allowing pretty much lossless transmission through the hole (kind of like a meta-material horn).

  • So if you take a solid surface... and make it not solid, then things of appropriate size can pass through the holes? ...
    Is this obvious science week or something?

  • Like transducers haven't been used in the history of mankind. Like ever. Acoustics is what acoustics is, dumbass.
  • ..is, by definition, no longer 'solid'.
  • Breaking news! If you put holes in a wall and poorly cover them, sound can pass through! We also have discovered that punching holes in a boat and patching them with paper allows water to leak in. -____-

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