Researchers say three-dimensional sound cloak is possible, in theory

Apparently not content with simply building an invisibility cloak, of sorts, those mad scientists at Duke University's Pratt School of Engineering now say that they've found that a three-dimensional "sound cloak" is also possible, in theory. According to Duke's Steven Cummer, the researchers have come up with a "recipe" for an acoustic material that would "essentially open up a hole in space and make something inside that hole disappear from sound waves." Needless to say, they haven't tested that possibility just yet, but they say it could one day be used to hide submarines from detection by sonar or even be used to improve the acoustics of a concert hall by making inconvenient structural beams effectively disappear. What's more, they say that the basic principles at play here could also suggest that cloaks could be created for other wave systems, like seismic waves, or even waves at the surface of the ocean, although the practical applications for those would seem to be a bit more limited.

[Image courtesy of Royal Navy/BAE Systems]

[Random Phycisist @ Mar 31st 2008 4:41PM]

Sound can be nullified by emitting a waves of the same amplitude, frequency and wavelength to perfectly overlap the incoming sound (though the sine wave would have to be offset by 90 degrees from the source sound). To my knowledge an automatic sound emitter is the closest you'd get to that, even then it would just produce a big patch of noise for the enemy to see. And then shoot at.

[CrowTree @ Nov 18th 2008 3:18PM]

Would someone discuss what they think is meant by the term 'acoustic material' that nullifies sound and what they think it would be made of?

[Peter @ Jan 10th 2008 1:00PM]

Does this mean they could deploy a three-dimensional sound cloak around Rosie O'Donnell's head?

[SimbaDogg @ Jan 10th 2008 1:57PM]

Impossible....its too big

[Jordan @ Jan 10th 2008 1:01PM]

Among other news: The entire Atlantic Ocean disappeared earlier today. Later on this on news at 11.

[Flashpoint @ Jan 10th 2008 1:10PM]

Anything is possible...in theory.
That's why they are called "theories" in the first place.

Similar to Hunt For Red October - Magneto Hydrodynamic Propulsion drives do exist,,,they've been tested in Japan. The only downside is, they don't give better speeds than current engine types.

[broli @ Jan 10th 2008 1:16PM]

Yeah, because you're comparing an engine which is in its gazillion'th generation to one in its first.

[Numetheus @ Jan 10th 2008 1:22PM]

Right NOW, yes. This is in its relative infancy when compared to current drive systems. Thats like saying the Model-T car was never a good vehicle because it doesn't have the speed of a Porsche. This technology will get better as it is developed over time. And besides, even in its current form, don't you think an engine with no moving parts has advantages over current engines, EVEN if it goes the same speed?

[josh @ Jan 10th 2008 3:21PM]

Actually, no, not everything is possible in theory. Theory has a very specific scientific meaning; for something to get the label of theory it must go through the entirety of the scientific process, withstand peer review, and be recognized by experts in that particular field. In short, for something to be considered a theory it must have a breadth of evidence supporting its plausibility and likelihood and is one of the most rigorously demanding labels to achieve in the scientific world.

The layman understanding of what theory means is horribly flawed and a testament to the absolute inadequacy of public school scientific curriculum and the pathetic level of basic understanding the american population has concerning science. Engadget misused the term here, and now so are you.

The only things possible in theory are those that are supported by a preponderance of evidence.

Sorry for the rant, but not understanding what theory means is actively hurting our society and letting crackhead notions try and stand at the same level as ideas that have withstood scrutiny for decades by the smartest minds in the world. Worse, society does not seem to care that they are using the wrong word, despite the fact that it is equivalent to Ted Stevens saying the internet is a series of tubes.

Engadget, you are professionals, please use the appropriate word (in this case something along the lines of "Researchers say results suggest three-dimensional sound cloak is possible") when reporting on science because it reflects as poorly on you as calling a DVD player a bluray player. It is the wrong term, and it is a major distinction. Everyone else, please try to learn what theory means. Our society lives by scientific and technological progress and being ignorant of the most basic simple concepts of science makes our society less capable in that regard.

[Wwhat @ Jan 11th 2008 2:17AM]

There's a more general use of the word theory you know, that's why you should perhaps specify "scientific theory" when you want to adhere to such standards as described.

SOED:
theory /"TIri/ n.. [Late L theoria f. Gk theoria contemplation, speculation, sight, f. theoros spectator (cf. THEOR), f. base of theasthai look on, contemplate: see -Y3.]
1 A mental scheme of something to be done, or of a way of doing something; a systematic statement of rules or principles to be followed.
2 Mental view, contemplation. (depreciated)
3 a The knowledge or exposition of the general principles or methods of an art or science, esp. as distinguished from the practice of it; Math. a set of theorems forming a connected system.

[josh @ Jan 11th 2008 9:58AM]

Well yes, but there is such a thing as contextual definition where one can determine the appropriate definition to use based of the context. In an article discussing the SCIENTIFIC findings of a SCIENTIFIC study, one might correctly assume that the SCIENTIFIC definition is most appropriate. Using one of the more lax terms would be incorrect in the context of this article.

Further, the modern dictionary definitions arise based off of popular usage, which is not the same thing as correct usage. I mean for crying out loud, MW accepted w00t as a viable dictionary word. If that doesn't reflect popular usage as a greater priority over correctness I don't know what does. The fact that dictionaries recognize the incorrect usage only reflects how poorly society understands what theory means, not that society is justified in holding to incorrect usage, ESPECIALLY DISCUSSING SCIENCE.

[Mitch @ Jan 10th 2008 1:23PM]

Awesome, so now what my wife says literally goes in one ear and out the other.

[Electromodo @ Jan 10th 2008 1:36PM]

This thing will make a great application for music studios and podcasters. Just paint your basement with invisible sound paint and your sound quality will soar! ;)

[bjorn_ahlm @ Jan 10th 2008 2:16PM]

The same is true for any rap concert!!

[Taylor @ Jan 10th 2008 2:55PM]

Wouldn't that let outside sounds IN too?
-Taylor

[Michael @ Jan 10th 2008 1:41PM]

Limited applications? Wouldn't a building made with a "seismic cloak" be essentially impervious to earthquakes? I suppose that is limited, but never the less important as all hell.

[josh @ Jan 10th 2008 3:44PM]

Not so much. Just because the inhabitants can't hear the earthquake doesn't mean the ground isn't shaking like crazy anyway. A bit of paint isn't going to stop the movement of 100 billion ton tectonic plates. Even if it did, I suspect current anti-seismic designs would be cheaper to implement and as effective.

[Mike @ Jan 15th 2008 7:32AM]

Maybe, but I suspect if the ground below the building disappeared, the building might too!!

[Nathan @ Jan 10th 2008 5:22PM]

@Michael

Case in point, not everything works in theory.

[it\\\'s a mario @ Jan 10th 2008 10:00PM]

@josh you're missing the point of a cloak. it's supposed to let the wave travel through it without interference, not to absorb the sound(which would make the effect on the building worse). I can't imagine such a cloak completely stopping the effects of an earthquake, but combined with anti-seismic designs this would protect us from even the worst of quakes.

[Wwhat @ Jan 11th 2008 2:23AM]

"The existence of an acoustic cloaking solution also indicates that cloaks might possibly be built for other wave systems, Cummer said, including seismic waves that travel through the earth and the waves at the surface of the ocean."

[buzzbean @ Jan 10th 2008 1:57PM]

Sweet Under water city here I come!!

[DC @ Jan 10th 2008 2:21PM]

The naval application is questionable. Modern submarines are actually already “too quiet”; sensors now just look for the quiet “pocket” amongst the water’s ambient noises. Why is there no sound coming from that submarine-shaped region of water?

[bcollinstex @ Jan 10th 2008 2:38PM]

That's what I was thinking. Just look for that spot that has no sound. If it's not attached to the floor, then it's probably a sub.

[Stimpski @ Jan 10th 2008 3:51PM]

Simple solution: populate the pocket of silence with simulated background ocean noise.

[it's a mario @ Jan 10th 2008 9:59PM]

you're missing the point of a cloak. Cloaks are see through, or in this case hear through, not camouflage or sound absorbent.

[Paul Brown @ Jan 10th 2008 2:42PM]

If it worked to guard against nagging wives, it would be worth investing in!!!

lol :)

[Will H. @ Jan 10th 2008 2:55PM]

This 'theory' also has possible implications for aeronautics - a major problem with super-sonic flight is sound, and it's also why major airports don't operate at night. In major cities, areas under the "flight-path" see decreased property values simply because of this noise. This type of technology may also be able to isolate passengers from much of the noise as well.

If aircraft became "silent", major airports would be able to operate flights 24/7, aeronautical engineers would be able to design super-sonic aircraft for all types of applications, etc etc.

[cybereality @ Jan 10th 2008 3:04PM]

Do I sense a Mass Effect?

[cromas @ Jan 10th 2008 3:31PM]

Everyone is talking as if this is a magic paint that you slather on something and the paint absorbs all sound. Huh? If it's a sound "cloak", that means the sound must go in one side and come out the other as if the object wasn't there. How could that possibly be used to reduce airplane noise?

[Wwhat @ Jan 11th 2008 2:27AM]

Since everybody is being a wiseass yet nobody bothers to read the links I'll do a paste:

"We’ve now shown that both 2-D and 3-D acoustic cloaks theoretically do exist," Cummer said. Although the theory used to design such acoustic devices so far isn't as general as the one used to devise the microwave cloak, the finding nonetheless paves the way for other acoustic devices, for instance, those meant to bend or concentrate sound. "It opens up the door to make the physical shape of an object different from its acoustic shape," he said.

[Wwhat @ Jan 11th 2008 2:28AM]

In other words, what if you could reflect the noise upwards? then it would help reduce noise at airports.

[JD @ Jan 10th 2008 3:40PM]

This technology prevents the reflection of waves, thus the "cloak" terminology. The use of this in concert halls may not be as useful due to the fact that sound would not travel beyond the "cloak", thus beams would still cause an acoustical problem to those beyond the beam - true, the echo off the beam would not occur, but that is only a portion of the problem. I suppose the next part of the problem would require some device to accurately reproject the sound out the other side of the object

[Otter @ Jan 10th 2008 3:42PM]

If it works with different kinds of waves, is it not possible that light waves might work eventually, making an optical invisibility cloak?

[John @ Jan 11th 2008 1:42AM]

I'm glad I wasn't the only one thinking that. Of course I've also opened myself up for flaming from the hard science nerds, in theory anyway.

[josh @ Jan 10th 2008 3:50PM]

You are comparing a property of mass to the prorogation of energy. Also light isn't a wave anymore than it is a particle. It is something that moves with properties of both a wave and a particle in a manner we cannot conceptualize. Thus we separate it out into saying it is both a wave and a particle and generally think of each independently.

Also, the same school has already achieved a bending effect with certain wavelengths of energy that much closer resembles an invisibility cloak that you imagine.

[josh @ Jan 10th 2008 3:52PM]

this was supposed to be a response to Otter, who posted just before this comment

[Jacob @ Jan 10th 2008 4:15PM]

This sort of ability has been around for quite some time now. Its better known as "muffliato".

[wrabbit @ Jan 10th 2008 4:24PM]

The problem with applying the same theory that is used for electromagnetic waves to sound waves, is that electromagnetic waves (and in particular light waves) exhibit both particle and wave properties. Sound waves however are pure waves, so you can't always apply the same rules to them, as it were, as for light.

Whether that affects their theory or not I don't know, the article doesn't go into that much detail. I will however say that what Cummer says "It was hard for me to imagine that something you could do with electromagnetic waves would be completely undoable for sound waves.", is not the kind of thing that a scientist should be saying - either you have a theory that backs up your assumption or you don't - imagination has nothing to do with it, at least in this case.

[Ed @ Jan 10th 2008 9:10PM]

So in theory (NOT Josh's use of the word), you could construct a pair of underwear to hide the sound of the "wind" in my pants?

There are already undies that can deal with the odor, but add this...

Full Stealth Super Undies.

[ironbridge @ Jan 11th 2008 6:40AM]

there used to be a theroy that if a railway carriage exceeded the speed of a horse the occupants would sufficate as all the oxygen would be sucked from their lungs....

and in the the 1940s the head of IBM predicted that there would only the need for 4 mainframes in the world!

also, Adolf Hitler is credited with saying that "the greater the lie and the bigger the deception the more the people will belive it!" - and who would belive that 60years the Americans relected George W Bush for a second term!

[sciencentral @ Jan 21st 2008 2:44PM]

For an amusing video on invisibility cloaking:
http://www.sciencentral.com/articles/view.php3?article_id=218393052