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Scientists Have Discovered a Shape That Blocks All Sound (fastcompany.com)
Scientists have developed an "acoustic meta-material" that can catch certain frequencies passing through the air and reflect them back toward their source. When a loudspeaker was placed into one end of a PVC pipe with a 3D-printed ring of the metamaterial, the ring "cut 94% of the sound blasting from the speaker, enough to make it inaudible to the human ear," reports Fast Company. From the report: Typical acoustic paneling works differently, absorbing sound and turning the vibrations into heat. But what's particularly trippy is that this muffler is completely open. Air and light can travel through it -- just sound cannot. The implications for architecture and interior design are remarkable, because these metamaterials could be applied to the built environment in many different ways. For instance, they could be stacked to build soundproof yet transparent walls. Cubicles will never be the same.
The researchers also believe that HVAC systems could be fitted with these silencers, and drones could have their turbines muted with such rings. Even in MRI machines, which can be harrowingly loud for patients trapped in a small space, could be quieted. There's really no limit to the possibilities, but it does sound like these silencers will need to be tailored to circumstance. "The idea is that we can now mathematically design an object that can blocks the sounds of anything," says Boston University professor Xin Zhang, in a press release. You can see a demo of the noise cancellation device here.
The researchers also believe that HVAC systems could be fitted with these silencers, and drones could have their turbines muted with such rings. Even in MRI machines, which can be harrowingly loud for patients trapped in a small space, could be quieted. There's really no limit to the possibilities, but it does sound like these silencers will need to be tailored to circumstance. "The idea is that we can now mathematically design an object that can blocks the sounds of anything," says Boston University professor Xin Zhang, in a press release. You can see a demo of the noise cancellation device here.
If it lets through normal air flow, can it be used for engine exhausts?
...a bawling kid at night in an airplane at 35,000ft.
If you could blot _that_ out I'd be well impressed.
That's the first application that come to mind.
sound dampening.
They are tuned to reflect the exhaust back at the piston to increase the compression... At least in model airplane engines that used alcohol. Haven't seen one of those in a while though.
Mostly random stuff.
It's a band reject filter, been used in acoustics for around 100 years. A narrow-band Helmholtz radiator that cuts ~1/30th of an octave in bandwidth. So it's great for a specific tone - but not broadband. And the dimensions of the elements (neck diameter, neck length, size of constrained volume) are proportional to wavelength, so what works in the demo at 1 kHz is massive at 100 Hz - and beyond house-sized at 20 Hz. This is just someone going "oh wow they can notch out a single frequency think about the impact!" when acoustics NVH guys have been doing it for 10 decades...
Browsing at +1 - no ACs, I ignore their posts. So refreshing!
Works for me.
I'm not sure of the name of the shape, but when we were younger, my wife could sit on my face so that I couldn't breathe... nowadays, I can't hear the stereo.
Happiness in intelligent people is the rarest thing I know.
Ernest Hemingway
Put up or shut up. File your patent and post the STL. I'll test it in a few hours lol.
Screw HVAC, can I please get this in the data center !?!?
Finally! You young kids with your loud music and your hula hoops...I can finally be rid of your noise noise noise! HA!
The cone of silence!
The article doesn't mention the limitations of this, but I'd expect that it would only work over a fairly narrow range of wavelengths. And the way it's designed doesn't seem to allow for the use of multiple rings calibrated for different wavelengths...
That said, high pitched sounds are easy to block with (relatively) thin insulation. If this could be made to block the lower end of the spectrum, without the large amount of insulation which that normally requires, I could picture this as being a nice development. Or if you have a mono-toned source of noise, like in the demo. I don't think that's very common though.
*sigh*
Since the editor and submitter didn't do it,
here is the BU research alert, which includes an image of the new material, and
here is a link to the published paper, from which you can get a DOI number if you want to read about their work.
The acoustic suppressor looks like thick a 3-d printed bushing.
The sound of my snoring goes from my bedroom, into the bedrooms of the guy upstairs, and the family next door. I need a way to block that sound.
If I could put some of that "acoustic meta-material" on the ceiling and wall of my bedroom, and block my snoring sound, that would be great. Hopefully the material blocks the frequency of snoring.
Maybe, but her ass was amazing!
One of the major hurtles with flying cars is the amount of noise generated during VTOL maneuvers.
Here's the paper published in Phys. Rev. B 99 in case anyone is interested: https://journals.aps.org/prb/abstract/10.1103/PhysRevB.99.024302
Clickbait.
Sounds like a helical version of this: http://www.deicon.com/tuned-ac...
No, that's your epic butthurt.
That's not a her.
So, theoretically, if one were to wrap one's wife in this material, then he wouldn't be able to hear her insist that he take the garbage out during the 4th period of the Warrior-Rockets game?
Asking for a friend.
You are welcome on my lawn.
Could it block very low frequencies ? Under 50 hertz
Only for extremely small values of "All".
Scientists Have Discovered a Shape That Blocks All Sound
No they haven't. At least, not according to the linked video in the article. It quieted it down quite a bit, but I could still hear it EASILY with the ring in place. It wasn't inaudible, not even CLOSE. Since they didn't put a ring of the same dimensions and material but in the shape of a simple, smooth, right, regular cylinder with a right, regular, cylindrical hole through it, centered and along the same axis as the material cylinder, (just like the "magic" ring but without the magic shape on the end,) while the speaker was generating the same sound at the same volume, to COMPARE it with. At least, that is, not in THAT video.
So this really is a non-story. Even if it quiets it quite a bit, it also occupies a LOT of the space, which RESTRICTS airflow, and likely adds a good bit of weight. (Imagine how big, thick, and therefore HEAVY it would have to be to fit the inner diameter of a big turbofan engine on a jet aircraft!) Then the output would need one too, and I understand the exhaust is pretty warm on one of those things, or at least can be. That may cause additional engineering challenges and cost, either of which could easily end up being insurmountable.
By the way, reflecting sound energy doesn't DESTROY it. It's ENERGY. Even if it DID work and DIDN'T add too much weight, and DIDN'T occlude the flow of air into and out of the engine to an extent that makes the plane unable even to take off under its own power, AND heat from the engine's exhaust wasn't a problem, etc., then the SOUND ENERGY being reflected INTO the engine will cause it to heat up even more. What are you going to do with all that extra heat? It's a LOT of noise, (and therefore, likely, a LOT of HEAT). Oh, and you're going to need a pair of these rings for EACH engine. How much weight will the required additional cooling cost? So you obviously will need much bigger, much more powerful (and noisier) engines. That will necessitate even bigger, thicker, sturdier rings, which will cause additional heat buildup... ETC.
If you're wondering how MUCH heat, well, it's actually pretty easy to work it out. Have you ever stood anywhere near a big turbofan jet engine, operating at, or at least near full power? Now imagine having to reproduce that sound, that same volume of noise, the same intensity... and while producing the same note, with a SPEAKER system. How big of an amplifier, in terms of Watts, would you need to do that? THAT'S how much sound power, (assuming you are somehow reflecting ALL of it,) we're talking about here. That much power is going to get trapped at BOTH ends of this hypothetical muffled engine. Where TF is it going to GO?
I see this tech as largely an interesting oddity, and will most likely come to nothing of any particular significance whatsoever in the world. Now maybe it MIGHT have some terrestrial applications, but don't look for this to be on aircraft anytime soon... that's my prediction.
Our reign has gone on long enough. Indeed. Summon the meteors.
The everpresent hum of central AC is very calming. As long as the outdoor temperature isn't expected to drop below 55, I turn it on in fan mode most nights as a white noise generator. At work it keeps stress low, whenever they turn it off for maintenance the silence throws everyone off.
It looks like interlocking spirals, so you could presumably spin it to adjust the 'length' of the spirals and change the frequency it cancels.
Suppose there is a dominant frequency in the noise, e.g. an engine note associated with revs, you could still use it to notch out that dominant note if you could control the spin.
There is a reason why the military's stealth helicopters come with thermite charges onboard that are to be set and ignited in the event of a crash or imminent capture. It's been LONG speculated that asymmetric props/rotors that work in conjunction with a silencer like this are one of the big secrets being protected.
literally night and day
Science in 2019, ladies and gentlemen, they LITERALLY produced NIGHT AND DAY
Wonder what the public key field is for?
you just need a wall of these around the kid and they'll reflect the sound back at the kid. I guess the size of the circles in the wall would need to depend on the frequency of the screeching. like, it's not an universal one size fits all(at least I don't see how it would be possible and they do speak about mathematically modelling for "any sound", needing different for different frequencies)
that's the theory anyways. still, it's fastcompany reporting. also it would need to be designed for the sound.
also I'm pretty sure you could still hear a speaker at 4%. the article doesn't make it quite clear what scale they were using. 0.05 out of .25 surely isn't 4% so maybe decibel.. the youtube demo video uses "microphone voltage level".
anyways, if it worked on with arbitrary soundforms on anything, surely a better demo would have been a harley - but it's supposed to reflect the sound back too, not absorb it into heat.
world was created 5 seconds before this post as it is.
Like the diesel electric trains, the Chevy Volt (IIRC), is only powered by electric motor. The gas engine only provides electricity to the motor/batteries, thus allowing it to operate at the most efficient engine speed when the battery is low. Since it only operates in a very narrow range, the exhaust can be finely tuned for that frequency. From what I have heard though, there is still room for improvement in this area... I'd really like to see a Sterling engine version though
All sound. Yeah, right. Clearly, the author of this article is not a nerd. Not even close.
I have paid all my bills this week!
What? I'd say their biggest breakthrough is finding that 94% = 100%.
Go look into something called "resonant turbocharging" -- you can use this to increase the charge pressure without moving parts.
This appears to be a tuned reflector. As such, it doesn't block all sound but reflects a single frequency. Maybe harmonics as well. An informative test would be to output white noise to the loudspeaker and give the spectrum observed by the microphone with and without the device in place.
I'm not saying this is without uses as a number of types of machine produce sounds predominantly at a single frequency. We imagine, for example, a vacuum cleaner with motor control tweaked to keep the motor at a particular speed, or an fixed speed engine in a hybrid car, or...
So they are cancelling sound... but not air flow. ... Even though that is literally the same thing.
I can only guess that it is a low-pass filter.
And the speakers emanated an "irritatingly high-pitched" "screching", but "you would see the loudspeaker's subwoofers thrumming away".
Which one is it?
A single driver, or a whole loudspeaker with a tweeter and a woofer?
I can only gues the author messed up.
And the articles are all way too vague. I wish I could imagine, how a ring would block a pressure wave going through its middle and e.g. not its sides, yet being blocked in the middle
I guess it only works if the pressure pushes against the ring wall too, whicb redirects it to cause destructive interference with itself on the pressure level.
Does anyone know morr?
The stupid mobile UI of /. does not support previewing, and the "Submit Anonymously" is right above the QWERT virtual keys.
I guess there's a reason I don't log in or come here often anymore.
Finally. A means to stop having to hear crap.
If a talk to you, the sound is around 60 tot 70 dB. A reduction of 12 dB gives a sound of 48 to 58 dB. You can still understand me speaking.
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You can get a lipstick that dispense this shape...
See, I have this rooster that won't shut up...
Come on, everything about this thing has been known for centuries (theories go back to Newtons time) and the fact that it (logically) can only work for a single frequency means it is completely useless for blocking broad spectrum signals.
None of the proposed use cases are going to work with this thing since it only filters a single frequency and almost all noise sources have a bandwidth to them. The proposed applications are simply idiotic given what this thing does.
Moreover, the statement that it will "cut 94% of the sound blasting from the speaker, enough to make it inaudible to the human ear," is TOTAL BULLSHIT as this represents only a drop of 12dB, which is hardly enough to render a random noise inaudible unless its already very quiet. And i say 'noise' but it is of course just a single frequency that is affected while real-world noise is just about an infinite set of frequencies.
Man, i wish i knew the ascii for facepalm. This article and the fantasies surrounding this research is mind boggling.
The worst part is that this is apparently a university making up fake stories to help them sell this tech.
Fuck these lying scum universities telling scum lies to promote their own lying scum asses.
Maybe useful as a highway sound barrier? Either as a replacement for the current walls to allow airflow, or in addition to.
You just know this isn't go to take the world by storm (for some as yet undisclosed reason) when the first press release you encounter is blathering on about silencing MRI machines for the benefit of people who are allergic to synthetic earplugs, and who can't, unfortunately, use the ones made out of solid steel, either, because of the intense magnetic fields.
Marketing person grappling with harsh reality: Gee, the HVAC people have all the volume, whereas the MRI people have all the money.
Probable end result: this fancy new technology gets installed in the HVAC system connected to the MRI room, so that no-one else in the hospital needs to listen to it hum 24/7.
Fundamental law of marketing: those who open their wallets on a lark have no money to spend, those who have money to spend open their wallets with great reluctance. Thus the sweet spot in the early going tends to be small.
Lip reading
Bouncing laser beams off vibrating objects
So obviously not very good for privacy then. And no, they didn't say it was either.
Jesus fuck, Slashdot editors. Did you fail basic elementary school math as well?
Still waiting on Serviscope_minor to wake up to fucking reality and realize that Jessica Price isn't going to fuck him.
Now if we can get all the riceburners to install these
Wives, politicians, brat kids, crying babies that people take to restaurants etc?
I approve of Trump needing to install these in his orifices. Just so long as it is him, one of his family, or one of the many "best people" he surrounds himself with.
Wonder if this would work for noise cancelling headphones too? It seems like its a ring that can be made smaller too: https://www.eurekalert.org/pub...
nice job
I approve of Trump needing to have these violently shoved up his ass. Just so long as it is him, his three most prominent kids (the creepy, hairy one, the stupid one and the feckless cunt), and all of the many "best people" he surrounds himself with, including their replacements, their replacements' replacements and their replacements' replacements' replacements. For extra measure, throw in that no-spika-da-inglich wife of his, at least until her contract runs out and she can finally divorce that piece of shit.
Emphasis mine (and most of the rest of the world).