9 ms·
An “acoustic metamaterial” that can cancel 94 percent of sound
- nicodjimenez 8y agoLike others here, I wonder how well this really works, but I applaud the effort nonetheless and I hope to see progress in this area in the coming years! Better sound blocking tech would really improve people's lives and stress levels, especially people who can only afford to live on busy streets in old apartments without proper sound proofing. No to mention people who want to do music in their apartments without bothering their neighbors.
- incompatible 8y agoI'm not sure how you could use it for that. Well, you could put a couple of those things over your ears, but earmuffs already exist. More likely it would be useful for building better mufflers onto noisy equipment. A muffler on musical instruments? I could imagine it fitted to a trumpet perhaps.
- afarrell 8y agoAs someone with disposable income working in an open office, I desperately want to know if this can be used to build something to cancel out human voices more completely than Bose QC-35s.
- zaroth 8y agoWhat you’re looking for is a Bose QC-35s... playing Metallica. Recent studies are mixed as to which has a more deleterious effect on creativity, the coworkers yapping or the heavy metal.
- afarrell 8y agoThat is my current strategy, though I’ve been using The Hu on repeat lately.
- lb1lf 8y agoCareful with those Bluetooth headphones, a colleague of mine managed to pair her laptop with her speakers rather than her 'phones, and then promptly proceeded with listening to a (veee-eeery) adult audiobook. Apparently, it can be quite difficult to determine whether the sound comes from your phones or outside them if you haven't turned the NC on. Fifty shades of embarrassing moments, that.
- wingerlang 8y agoI just got a pair, every time I start music I tend to mute it and slowly increase volume until I am sure where it comes from.
- Tade0 8y agoI have a pair and I can attest to that. Unfortunately.
- swinglock 8y agoNot consuming porn at work is also good a way to avoid embarrassment...
- ianai 8y agoYes, was it somehow tolerable that she was listening to porn?
- Sylos 8y agoThe trick with this material is that it pretty much reflects sound waves. On the way back, these reflected sound waves then crash into the upcoming soundwaves and they cancel each other out. Headphones with active/acoustic noise cancelling use the same trick, except that they pick up the upcoming sound waves with a microphone and then use a speaker to generate those "reflected" soundwaves. Actually-reflected soundwaves cannot be as strong as the upcoming soundwaves, so they're never going to fully cancel out the noise. Those generated soundwaves can. One point is that there's most likely less latency for a soundwave to get reflected vs. picked up by a microphone and then generated by a speaker. However, to my knowledge our human senses have even more latency than both of those, so I don't think that matters.
- petra 8y agoThe latency in the active noise-cancelling systems is a few milliseconds, mostly due to processing time. That's why they are less capable in filtering non-repetitive noises like speech, especially their higher frequencies.
- hatsunearu 8y agoThis is a very bad meme that's been propagated so much across the internet. 1. The latency is active noise cancelling systems is very low; much less than the frequency of most sounds. 2. Noise cancelling is ineffective at higher frequencies because the space between the speaker driver and the ear becomes large enough that the destructive interference becomes imperfect. 3. The feedback has to come from somewhere, and once the frequencies become high enough, the phase shift caused by the physical distance between the driver and microphone start to affect the feedback loop. 4. Because of these issues at higher frequencies, they just lower the feedback gain at higher frequencies. This effectively makes the active noise cancellation system be not sensitive to higher frequencies. 5. This is very much akin to frequency compensation in other topics like buck converters and op amps--the additional phase shift in the feedforward path that often increases as frequency goes up becomes problematic to compensate, so they just make the feedback loop insensitive to that region. ----- the quick way to debunk this is two tests: 1. Play some bandlimited noise (https://www.youtube.com/watch?v=5qV5j9wD5e8 https://www.youtube.com/watch?v=5qV5j9wD5e8) really loudly and I guarantee you any shitty ANC headphone will cancel this out just fine. Noise by definition is non-repetitive. 2. Play a high frequency sinusoid (https://www.youtube.com/watch?v=TRKB5kWs7KE https://www.youtube.com/watch?v=TRKB5kWs7KE) really loudly and it will go straight through any ANC headphone. A sinusoid is as repetitive as it gets.
- VanPossum 8y agoSince you mention disposable income, if you can tolerate in-ear monitors I would suggest getting custom-fit silicone IEM. Used with even a very low level of music (or even some white noise generator) they dampen noise like nothing else in my experience. Successfully tested in a work environment with endless yammering, bleeping computer equipment, that mandatory 'shout-speaking' colleague, and even once a guy who let a 1U server running on his desk for a week for testing purposes (because why not). The only down-side for me was that they are not as quick to pop on and off as regular headphones.
- snvzz 8y agoNot a fan of the QC-35. I find their ANC headache-inducing, and while the overall sound signature is very good, it's only because of built in DSP doing EQ. The distortion is unbearable. Thus I use the audio-technica MSR7 at work. At home, I don't need isolation, so I enjoy sennheiser's HD600.
- jaggederest 8y agoEarplugs under the headphones?
- deegles 8y agoFor voices you need passive sound isolation, not active noise cancelling. Try these: Howard Leight by Honeywell Sync Stereo MP3 Earmuff (1030110), Black https://www.amazon.com/dp/B004U4A5RU/ https://www.amazon.com/dp/B004U4A5RU/ They also give off a very strong “I’m busy” vibe If that’s still somehow not enough, wear these concurrently (this is great for planes too): Etymotic High-Fidelity Earplugs, ER20XS Standard Fit, 1 pair, Polybag Packaging https://www.amazon.com/dp/B00RM6Q9XW/ https://www.amazon.com/dp/B00RM6Q9XW/ Also recommend the above with these foam tips for longer wear, I’ve done up to 16 hours with only a little discomfort: Shure EABKF1-10M Medium Foam Sleeves (10 Included/5 Pair) for E3c, E4c, E5c, E500PTH, i3c, i4c & SE Earphones (Black) https://www.amazon.com/dp/B0015PN3W6/ https://www.amazon.com/dp/B0015PN3W6/
- porker 8y agoHow about for lower frequencies: motorways, busy roads (no individual car noises; a solid background roar)? They make having the window open here a nightmare.
- jfries 8y agoIsn't this exactly when active noise cancelling works the best?
- QuantumGood 8y agoI've had these for a year and like them: Professional Safety Ear Muffs by Decibel Defense: amazon.com/gp/product/B01BEENYCQ/
- eeZah7Ux 8y agoActive noise cancelling is overrated. Use passive isolation.
- imtringued 8y agoNo, -12db is inferior to most earplugs.
- ken 8y agoI've found that musician earplugs under ear defenders essentially cancels all sound, including human voice. It's not something I would recommend. It makes me feel uneasy. A dozen people could walk up behind you and watch you work, and you'd never know until they tapped you on the shoulder. If you have any anxiety at all about this, true silence will make it far, far worse. Noise isn't the only problem with open office layouts. It's just a convenient way to describe it to people who don't understand. If you think it's hard to talk to business people about the problems caused by excessive sound levels, imagine how difficult it is to talk to them about how you feel. At some level, though, they do know this. Your CEO doesn't have his desk facing the door of his office because that position is the quietest. Try do-si-do'ing his desk one day and see how long that lasts.
- deleted 8y ago[deleted]
- tmikaeld 8y agoAs far as deep bass goes, this won't hinder that - since bass waves have too high of a pressure to not pass through the object. The most effective material is high mass and flexible, like cork or hemp crete. Bass-traps also exist, they eat up the energy of sound pressure and are usually large tubes and many of them are needed to make a difference. So there's a reason that this test is on high-frequencies, not low ones. EDIT: Fine, down-vote me if you want but it doesn't make it less true [1] [1] https://www.acousticfields.com/how-do-you-stop-low-frequency-issues-in-a-small-room/ https://www.acousticfields.com/how-do-you-stop-low-frequency...
- simonebrunozzi 8y agoI am surprised to read that you were downvoted by some. Even if you are completely wrong (I have no idea, I am not a sound engineer), you are trying to provide an opinion and I would simply debate it with you, rather than downvoting.
- deleted 8y ago[deleted]
- BossingAround 8y agoLately, I have noticed a lot more downvoting going on than I was used to. Maybe a confirmation bias on my part, but sad nevertheless... I'd use downvoting only for submissions that are harmful.
- vanderZwan 8y agoThe longer this website is around, the more people there will be with enough karma to be able to downvote in the first place. Perhaps that explains the shift you've seen? If so then perhaps the weighing of upvotes/downvotes should be adjusted to reflect that change in voting power?
- fulafel 8y agoThe article mentions on one hand a high pitched note, but on another hand enough bass to see the subwoofers play it: "Standing in the room, based on your sense of hearing alone, you’d never know that the loudspeaker was blasting an irritatingly high-pitched note. If, however, you peered into the PVC pipe, you would see the loudspeaker’s subwoofers thrumming away."
- mjmj 8y agoIf affordable, all I can think about is how much this could help musicians or bands that practice at home without disturbing the neighborhood.
- lolc 8y agoIf you want to feel the kick of your drum, your neighbours will hear it too. This gadget won't help.
- chrismorgan 8y agoWhat does it mean to “cancel” or “block” “94% of sound”? From the paper’s abstract: “Finally, the proposed unit-cell performance is validated experimentally, demonstrating a reduction in the transmitted acoustic energy of up to 94%.” Does this basically mean amplification by about −12 dB?
- tszyn 8y agoI guess so, but when you use energy instead of pressure, and a linear scale rather than logarithmic, it makes the results look more impressive.
- deytempo 8y agoIt places the lotion in the basket...
- ScottBurson 8y ago"Cancel 94%" sounds like a lot, but that's just -12dB — significant, certainly, but nowhere near making audible sounds inaudible.
- deleted 8y ago[deleted]
- abainbridge 8y agoAnd for comparison, a single 4mm pane of glass is about -27db, and cheap commodity wall board is about -46db (https://www.insulationsuperstore.co.uk/product/soundboard-3-acoustic-wall-board-46db-reduction-1-2m-x-1m-x-24mm.html https://www.insulationsuperstore.co.uk/product/soundboard-3-...)
- earthicus 8y agoFor those of you who haven't yet read the article, the cool thing about this new technology is that the material is not a solid plane, but an empty ring that allows air to pass through: https://www.bu.edu/research/files/2019/02/acoustic-metamaterial-noise-cancellation-device-19-1023-SOUND-060-2.jpg https://www.bu.edu/research/files/2019/02/acoustic-metamater...
- romwell 8y agoSo, essentially, they invented a silencer/muffler? Certainly interesting, but the applications of that would be somewhat niche. To be specific, there are not that many scenarios where a solid wall won't do, but a honeycomb-like barrier is OK. Aesthetics are important, but musicians in a studio couldn't care less about how stuff looks as long as it works (and so do your musicians' neighbors). One good application, as others have mentioned, is putting that thing around a fan, to minimize noise (a solid barrier defeats the purpose of a fan). I wonder what else would be a killer feature application of this kind of structure.
- TheOtherHobbes 8y agoAnd it's very unlikely to be a broadband attenuator. Attenuating a single frequency is a neat trick, but most acoustic applications require require something that works a wide frequency range. Given the breathless tone and the curious turns of phrase, I strongly suspect the author has no background in sound, acoustics, science, or journalism.
- danjayh 8y agoThe article implies that the test stand was running at a fixed frequency. This makes me suspect that this has to be designed to interfere with transmission of sound at a specific frequency, and perhaps isn't capable of eliminating more complex sounds like voices or music.
- lolc 8y agoThe title of the article is incomplete. It should read > An “acoustic metamaterial” that can cancel 94 percent of sound _at one frequency_. I don't see how that could counter the turbulence generated by a jet engine. Maybe that was just the journalist getting ahead of themselves.
- petra 8y agoIs it possible to build this at home using a 3d printer ?
- romwell 8y agoIt appears that that's exactly how they made it. What you end up with, though, is a pretty specific muffler. Making a wall out of these blocks will take a while, and it'll only block a narrow range of frequencies, somewhat. But hey, it's better than plywood because you can, like, stick your hand through it! And it's hi-tech!
- sosuke 8y agoSign me up! I’d love to muffle my GPU miners. They need air and make plenty of fan noise.
- m0zg 8y agoToo bad sound perception is logarithmic. 94% is nowhere near as much as one would be led to believe if one did not know what a "decibel" is. Which is just as well I suppose: makes for a very nice, clickbaity headline. _Many_ people don't get this. People are surprised to discover that a 10W guitar amp is not that much quieter than a 100W one, and even 1W amp can be pretty darn loud, even though it's just 1% of the power.
- edoo 8y ago-12dB on a drone could mean the difference between regulatory approval or not.
- jaclaz 8y agoAs a side note, I know that I am old (and grumpy) but was it really necessary for the actual engineers to pose for the leading article picture? I mean if it was a journalist's or editor's choice to mis-illustrate the invention creating a picture with models I would be fine with it, but the actual engineers/inventors posing for it?
- deleted 8y ago[deleted]
- WilliamEdward 8y agoIn physics we are learning about sound waves, and how noise cancelling headphones detect noise and produce waves which are destructive to those incoming sound waves, by matching the amplitude and sending them out at a different time interval. I think future noise cancelling materials will make use of some kind of tech like this. I don't think materials that simply absorb sound are very efficient.
- saagarjha 8y agoThis, being an active process, would require energy would it not?
- intertextuality 8y agoDid... no one read the article before upvoting? This can reduce specific frequency sounds by -12db, NOT 94% of "sound". Can /u/dang or someone edit this clickbait title? The wavelength of 100hz is 56.5 feet. While it may be possible that these rings can attenuate specific high frequencies, they don't [and cannot] reduce all sound in general. To say otherwise would be to defy physics. Assuming the rings aren't vaporware, they could work for specific, constant higher frequency sound sources, like machine hums as mentioned in the article. However, the rings' aesthetic would be useless inside of an MRI machine... There is a reason existing sound barriers aren't open, because even regular walls block high frequencies. (And not just specific ones that match to a ring's size). The best way to kill frequencies are thick objects (like walls). For a room (like a editing studio or recording booth), it should have a non-symmetrical wall with various recessed spaces to function as sound baffles, at the least. And lastly, these would be completely useless for low frequencies.
- atoav 8y agoA useful application would be e.g. in cases where you want to target specific frequencies AND airflow should be possible. So this could be useful for attenuating small computer fans by 12 db without or adding meandering pipes filled with absorbing foam. For general acoustics I'd stick to a accuratly calculated and well built diaphragmatic absorber or at least a helmholtz absorbers.
- phasetransition 8y agoMinor pedantry: 10log(6/100) = -12.2, so you could sort of get the number stated if you assume they meant sound power. These metamerial, interference based approaches, are not going to be broadband by the standards of physical acoustics. This could be useful for helping cancel a particular harmonic of a helmholtz resonator. The real question, to me, is does it still work at high transitional Reynolds numbers, or under full turbulent flow? Source: End effects during transitional and turbulent flow for Helmholtz resonators (i.e. bass reflex ports) in high output pro-sound loudspeakers has been something I've played around with in the past.
- hatsunearu 8y ago
- hatsunearu 8y agohttps://journals.aps.org/prb/pdf/10.1103/PhysRevB.99.024302 https://journals.aps.org/prb/pdf/10.1103/PhysRevB.99.024302 Anyone have access to this paper? This is driving me nuts and I want to know, damn it :P
- rezreza 8y agoJust couple of points about the article. 1- the main focus of the study is to silence the sound while maintaining ventillation, i think comparison with the barrier is not relevant. 2- the structure is deep subwavelength compare to the mufflers size 3- low frequency can still be silenced with this design but need an stiffer material maybe metal 4- experiment is design considering both fabrication limitation ( 3D print size) and the tube material to be effectively work as a waveguide
- rezreza 8y agoPlease Read the actual article
- tylerg 8y agoSo what are the best, most creative ways to get rid of freeway/steeet noise from your yard?
- Mizza 8y agoI feel like a lot of the comments here are missing the point because this isn't a magic noise-cancelling material. The neat thing about this is that it works while still allowing air to flow through. Even if it's not blocking broad spectrum sound, it's still useful to block specific narrow frequency ranges. One immediate application mentioned in the article is for drones, which are very loud. Maybe if you put these devices below the fans of a drone, you could make it run much quieter. It also establishes acoustic metamaterials as a new field of study, so we could soon see significant improvements in this technology - imagine a dynamic version of these rings which can change the frequencies which they block.