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

First time accepted submitter benonemusic writes "Researchers have devised a means of making sound transmit easily through rigid surfaces, including walls. The process relies on creating small holes on a wall, and covering them on one side with a thin covering made from plastic wrap."

Comments

Why would you do this

[Anonymous Coward]

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

Re:Why would you do this

[WillgasM]

If only there was an article enumerating possible applications of this technology.

Re:Why would you do this

[JustinOpinion]

Well, TFA 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 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).

Re:Why would you do this

[Anonymous Coward]

How nasty could it be? That baby was all up in that not too long ago.

Thank god the research is finally paying off

[Anonymous Coward]

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?

Re:Thank god the research is finally paying off

[NatasRevol]

Those well engineers suck at building walls.

And in other news...

[RdeCourtney]

Researchers find that by putting a glass to a wall, helps sound travel through rigid surfaces as well.

Re:And in other news...

[lxs]

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."

As an apartment dweller

[sl4shd0rk]

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

Re:As an apartment dweller

[judoguy]

There is vinyl sheeting for just this purpose.

Mass Loaded Vinyl 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.

Re:As an apartment dweller

[master5o1]

If she doesn't make a sound, you're not doing it right.

FTFY.

New NSA-Approved Building Code

[justthinkit]

New NSA-Approved Building Code

Re:New NSA-Approved Building Code

[Anonymous Coward]

I believe this building technique has already been used on my apartment building...

Let's see them patent the drum all over again

[icebike]

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

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

Re:Let's see them patent the drum all over again

[jeffmeden]

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

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:Let's see them patent the drum all over again

[sir-gold]

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

Re:Let's see them patent the drum all over again

[archshade]

There's also a use in controlled/clean rooms. You can already get some something similar, there called Talk-Throughs (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.

Finally

[ArcadeMan]

Spying gear for Bond. Amish Bond.

Is it one way or bidirectional?

[niftymitch]

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.

And the downsides not mentioned.

[queazocotal]

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.

More info...

[slew]

Some complementary work done at UT-austin

Instead of a membrane matching the impedence of a "meta-material" made by punching regularly spaces in a wall (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).