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MIT researchers develop a paper thin loudspeaker

374 points by go_prodev 4y ago

Kaibeezy 4y ago
Seems so obvious once described. It doesn’t explain how well the tiny domes reproduce low frequency sound, since they displace very little air.
- ptha 4y ago
  Yes it would be nice to get a some comparison of fidelity, range etc. It mentions high-quality sound. But it does seem more efficient than traditional speaker designs. From the article: They tested their thin-film loudspeaker by mounting it to a wall 30 centimeters from a microphone to measure the sound pressure level, recorded in decibels. When 25 volts of electricity were passed through the device at 1 kilohertz (a rate of 1,000 cycles per second), the speaker produced high-quality sound at conversational levels of 66 decibels. At 10 kilohertz, the sound pressure level increased to 86 decibels, about the same volume level as city traffic. The energy-efficient device only requires about 100 milliwatts of power per square meter of speaker area. By contrast, an average home speaker might consume more than 1 watt of power to generate similar sound pressure at a comparable distance.
  - chrisco255 4y ago
    The article has a video of the speaker playing "We Are the Champions" by Queen. It's clearly muffled quite bit, but damn good quality for a paper thin speaker burning just 100mW.
    - martyvis 4y ago
      Actually it's 100mw per square metre, so maybe that small speaker was only a couple of milliwatts
  - dotancohen 4y ago
    Sounds perfect for a cellphone. Imagine theater sound - or even a decent loudspeaker conversation.
  - buescher 4y ago
    That's a 10db difference in efficiency, which just means it's an efficient speaker, maybe not as efficient as a good horn-loaded speaker.
  - eimrine 4y ago
    > But it does seem more efficient than traditional speaker designs. The numbers you have mentioned do not tell that. I have a pair of 4W speakers which can make impossible any dialogue in a 15m^2 room if working on full loudness. The secret is big but lightweight moving parts (diffusor of big square) and absence of bass.
isoprophlex 4y ago
> To overcome this problem, the MIT team rethought the design of a thin-film loudspeaker. Rather than having the entire material vibrate, their design relies on tiny domes on a thin layer of piezoelectric material which each vibrate individually. These domes, each only a few hair-widths across, are surrounded by spacer layers on the top and bottom of the film that protect them from the mounting surface while still enabling them to vibrate freely. Whoa, does this mean an array of individually addressable micro-speakers becomes feasible? Like pixels in a computer screen, send different signals to each tiny speaker? That would mean craaaazy spatial audio, if I'm not mistaken.
- boomlinde 4y ago
  It seems like there's no reason for this use case for the speakers to be individually addressable, and that would probably add significant complexity.
  - moffkalast 4y ago
    That would be pretty nuts, sending out a digital signal and have a built-in DAC for each emitter. Probably way too much bandwidth for any of the standard busses though.
    - oblio 4y ago
      The thing is, don't we have a ton of higher bandwidth buses already available? I can't imagine the audio interfaces being faster than HDMI 2.0, USB 4/Thunderbolt, DisplayPort 3, etc.
      - moffkalast 4y ago
        I was thinking more in the line of i2c, i2s, spi, uart, since I think all of those that you listed require very extensive circuitry to parse. (At least that's the motherboard makers' excuse to only include like 2 USB 3.0s and 1 USB 3.1 port and like two bazillion 2.0 ports)
    - 4y ago
moffkalast 4y ago
Very cool! Though it looks like it has the same problems DML has, in that it's hard to get good bass out of them. If nothing else it would be quite useful for IoT applications, replacing ol' piezo buzzers, taking up less space and being more efficient.
natly 4y ago
Really cool stuff > Used this way, the thin-film loudspeaker could provide active noise cancellation in clamorous environments, such as an airplane cockpit, by generating sound of the same amplitude but opposite phase; the two sounds cancel each other out. Not mentioned here is that to achieve this you need to track heads in real time (i.e. with a camera) - the phases need to align at just the right spot - which might be worth the creepiness tradeoff or not idk.
- olivierduval 4y ago
  Actually, it looks more like isolating the whole cockpit (or room) with the "paper" to the noise is cancelled before entering the cockpit. You could imagine a recording studio with 2 sheet of this: - sheet against the wall to cancel the outside sounds coming INTO the recording room - sheet against the previous one (but turn oppositerly) to cancel the sound from the recording room to go outside the room The contact sheet between both would stay fixed
  - Applejinx 4y ago
    Neither of those things would work because the objectionable noise is deep into the bass, which this stuff can't do with the excursion limits it's working with.
- twayt 4y ago
  I wonder what kind of discordant noise it might produce if the heads are misaligned.
danaos 4y ago
Paper: https://ieeexplore.ieee.org/document/9714188 https://ieeexplore.ieee.org/document/9714188
t-3 4y ago
So, this looks like basically a flexible electrostatic speaker? Which means almost no bass and highly directional?
- falcolas 4y ago
  Not quite, since an electrostatic speaker requires the surrounding layers to be electrically charged to move the diaphragm. This appears to be closer in form to a piezo (or array of piezos) where the diaphragm itself moves under the electric charge.
- Applejinx 4y ago
  Not exactly. This isn't a dipole, it's expanding and contracting across its whole surface. So, almost no bass (no excursion) and not as directional as if it were a dipole. Electrostatics put out the inverse wave behind them, this is either mounted on a rigid object (no back radiation) or in free air (in-phase back radiation, and front radiation is half as powerful as it would be against an object)
amelius 4y ago
Cool, imagine wall-paper made out of this stuff ... Could it disrupt the hifi speaker market?
- deleted 4y ago
  [deleted]
- Sebb767 4y ago
  > Could it disrupt the hifi speaker market? Most likely not. The sound quality will probably be far below what you get with normal speakers at the same price point, not exactly what audiophiles are looking for.
moron4hire 4y ago
If they can make this transparent all the way through, it might be useful for creating tactile interface on capacitive touchscreens.
- mlatu 4y ago
  oooh, yes that too. but even opaque you could use it for haptics: VR gloves and similar
dsr_ 4y ago
They keep saying "high quality" but the article does not justify that in any way. It's an MIT press release. The major flaw of the article is that it does not link to an actual paper.
- cjg 4y ago
  It was in another comment: https://ieeexplore.ieee.org/document/9714188 https://ieeexplore.ieee.org/document/9714188
  - layer8 4y ago
    Paywalled though.
- falcolas 4y ago
  > but the article does not justify that in any way. In a way, they did. They said that the 1kHz tone was "high quality", which most likely means it reproduced the waveform they sent fairly accurately. Of course, it's not a complete answer, and I too would appreciate the actual paper. "When 25 volts of electricity were passed through the device at 1 kilohertz (a rate of 1,000 cycles per second), the speaker produced high-quality sound at conversational levels of 66 decibels." Not sure if it matters, but the fact that it's producing ~10x (2^3.333) the sound pressure (which is around 4x louder by human perception) at 10kHz vs 1kHz is vaguely concerning. It would require a fair bit of additional resistance to try and get a "flat" loudness across the spectrum, especially since human hearing is more sensitive at higher frequencies. Absolutely doable, but it means the speaker film can't just be used out of the box.
- Applejinx 4y ago
  High quality could mean that it produces high efficiency at its optimal frequency, or that it can be cut and bent and shaped any way you want. They're probably not talking about or even understanding 'audio quality' in the sense of 'is this going to replace your Magnepans or electrostatics?'. As designed it will not. It might make for a great tweeter or mid-and-up driver, though. No reason you couldn't put it ON a big ol' flat panel woofer (or whatever suitable shape is best). Then it becomes a coaxial, and maybe there are big wins along that path. If it's light, just sit it ON the bass driver and that does your excursion. The surface layer adds all the mids and highs.
dr_dshiv 4y ago
There are lots of small voice coil speakers that you can attach to a table or window to turn it into a speaker [1]. Anyone know what the advantage of the paper thinness is? [1] search for “surface transducer”
- jacquesm 4y ago
  I've glued four of those to the soundboard of an elderly Yamaha G2 to give it some interesting capabilities.
  - tambourine_man 4y ago
    That sounds (hehe) interesting. Do you have some video or more info to share?
    - jacquesm 4y ago
      Apologies for the crappy playing (this was still very early days): https://www.youtube.com/watch?v=6BqYQdKn0UA https://www.youtube.com/watch?v=6BqYQdKn0UA The original piano of course still works (but can be disabled with a slide) so you can either layer multiple instruments or change instruments altogether (instant organ, for instance). The amp is really tiny, it probably doesn't put out more than 5 W but the soundboard serves as a natural amplifier and with the sustain pedal open the whole thing comes to life. The main use of this feature is to play the 'other' hand while practicing, it sounds a lot more natural when it comes through the soundboard rather than the tinny speakers in the PC. You can use any kind of midi based synth for that, I'm using various synths and Pianoteq on Linux.
      - tambourine_man 4y ago
        That’s very cool, thanks for sharing!
- falcolas 4y ago
  As I understand it, this can be attached directly to any surface, including completely dead surfaces (for example, a piece of fiberglass/mineral wool insulation), without impacting the sound.
dt2m 4y ago
> When 25 volts of electricity were passed through the device at 1 kilohertz (a rate of 1,000 cycles per second), the speaker produced high-quality sound at conversational levels of 66 decibels. At 10 kilohertz, the sound pressure level increased to 86 decibels Read: Tinny af. Nonetheless, VERY exciting technology. Will be interesting to watch as it matures.
- cushychicken 4y ago
  Could likely compensate that with digital EQ, though.
  - layer8 4y ago
    Bass frequencies are inherently impossible with that kind of physical design. To move enough air at low frequencies, you need more physical depth (higher amplitude).
    - kierenj 4y ago
      Wouldn't the accumulated effect be viable though? I mean, air molecules are tiny, but there are lots of them vibrating in a coordinated way to make bass..
      - layer8 4y ago
        Just compare the surface area and displacement of the actual tiny domes with the surface area and displacement of a bass-capable loudspeaker membrane. If you do the math, I don’t think there’s any chance.
        im3w1l 4y ago
        Could you get a balanced sound if you cap the volume? Like maybe the domes can't do 60dB of bass, but what about 20?
        deleted 4y ago
vardump 4y ago
Sounds (ahem) a lot like Audio Pixels, from about 10 years ago. I wonder whether anything real ever came out of that? At least looks like they have a web page, https://www.audiopixels.com.au/ https://www.audiopixels.com.au/.
- goodmachine 4y ago
  Audio Pixels are going down a somewhat different route (MEMs to produce a speaker-on-chip) From the latest shareholders report: "devices were measured and demonstrated to reproduce a near flat frequency response from 100Hz through 50KHz This pioneering achievement for the first time makes it possible for a single device to reproduce crystal clear sound throughout the audible spectrum ‐ without imposing the tradeoffs required by conventional speaker technologies to achieve quality sound through the utilization of separate drivers to reproduce the low, mid, and high frequencies" That said, they've been working on this idea for some time, no indication of when if ever a viable mass product will land
mlatu 4y ago
Also, HAPTICS! i mean, you could use this to make haptic gloves and similar gadgets for VR
- layer8 4y ago
  I don’t think each dome is individually addressable. The general problem with that is the huge amount of traces (wires) you need to route for individual control. And if all domes emit the same vibrations, you just get a vibrating glove, not fine-grained haptics.
  - mlatu 4y ago
    it's a phasearray, therefore you are bound to have some x/y control. also, look at your screen and tell me more about lots of traces.
    - layer8 4y ago
      Screen pixels store their state and are updated in sequence, not simultaneously (hence the “jelly scroll” effect), and only at low-for-sound frequencies (60-240 Hz nowadays).
      - mlatu 4y ago
        ever touched a strung guitarstring? the highest string, 5 or 6. fret: 400Hz im not saying this can just be tailored into haptics AS IS of course you will need to put some work into this, but having hardware like this opens up many possibilities if i were you, i wouldnt just dismiss the idea (just because you cant see how to implement it, doesnt mean noone else wont)
        layer8 4y ago
        I’m not dismissing the idea, I’m saying that the design presented doesn’t seem to bring us that much closer to solving the actual problems with implementing high-resolution haptics. People tend to severely underestimate the difficulties.
ourmandave 4y ago
Reminds me of Vogons... People of Earth, your attention, please. This is Prostetnic Vogon Jeltz of the Galactic Hyperspace Planning Council. As you will no doubt be aware, the plans for development of the outlying regions of the Galaxy require the building of a hyperspatial express route through your star system. And regrettably, your planet is one of those scheduled for demolition. The process will take slightly less than two of your Earth minutes. Thank you.
- pbhjpbhj 4y ago
  Wrong thread?
  - evilotto 4y ago
    Right thread. Every tin can, every dust bin, every window, every car, every wine glass, every sheet of rusty metal became activated as an acoustically perfect sounding board. Before the Earth passed away it was going to be treated to the very ultimate in sound reproduction, the greatest public address system ever built. But there was no concert, no music, no fanfare, just a simple message.
phasersout 4y ago
Pretty cool, but you still need a big ass subwoofer for the low end..
MrBuddyCasino 4y ago
Transducers are nothing new, and piezo speakers are nothing new. That said, this might improve audio in constrained spaces such as wristwatches, smartphones or laptops, because you can re-use existing larger surfaces. It will probably not replace traditional speakers due to simple physics: sound pressure depends on displacement volume, which means area * excursion. Piezo crystals are not very flexible and have weakness in sound reproduction. They were used in cheap tweeters for some time, but have fallen out of fashion because at higher volumes they start to "scream" in a very unpleasant way. The higher excursion requirements also means they cannot be used for low frequencies. Acoustic short-circuit also means that you cannot just have a thin paper-like loudspeaker, as the waves from the front and the back cancel each other out (this does not apply to wallpapers).
biccboii 4y ago
thomasfl 4y ago
This is a good example of the first principle, made famous recently by Elon Musk. If you identify the problem and common assumptions, you will probably ask yourself if a few vibrating loudspeakers is simply what everybody is doing. Lots of tiny loudspeakers working in unison, could actually produce sound cheaper and better.
- JohnJamesRambo 4y ago
  Yes it is very Elon-like because unless I’m misunderstanding the article this has been done many times before and has massive drawbacks not mentioned in the press release. https://en.wikipedia.org/wiki/Distributed_mode_loudspeaker https://en.wikipedia.org/wiki/Distributed_mode_loudspeaker You can buy your own for $15 at Parts Express. https://www.parts-express.com/Dayton-Audio-DML25-4-2-Distributed-Mode-Loudspeaker-Transducer-20W-4-Ohm-295-236 https://www.parts-express.com/Dayton-Audio-DML25-4-2-Distrib...
  - staindk 4y ago
    Yeah was going to say, this reminded me of this[1] video (series of videos actually, but this is the first in the series). Interesting stuff. [1] https://www.youtube.com/watch?v=zdkyGDqU7xA https://www.youtube.com/watch?v=zdkyGDqU7xA
duckmysick 4y ago
Could this process be reversed to produce paper thin microphones?
ZoomZoomZoom 4y ago
If there's multiple sound sources on a plane, how will it deal with phasing issues, when the distance between opposed points is significant?
DrBoring 4y ago
I wonder if this tech will lead to better quality audio from toys/books/greeting-cards that produce sound. I often wonder if the poor quality in such applications is due to the tiny speaker, or a mixture of the playback hardware and low audio bitrate. > the thin-film loudspeaker could provide active noise cancellation in clamorous environments, such as an airplane cockpit, by generating sound of the same amplitude but opposite phase; the two sounds cancel each other out. What would such an environment sound like? For example, how far would your voice travel when speaking to the person sitting next to you?
- tristor 4y ago
  > I wonder if this tech will lead to better quality audio from toys/books/greeting-cards that produce sound. Possibly. Eventually. We already have very high quality tiny sound drivers, they’re used in IEMs. They’re expensive though. The quality of the applications you asked about is mostly limited by BOM cost. If this new speaker can get it’s cost down, it seems like a big win especially for places that are space limited in depth.
  - 323 4y ago
    > We already have very high quality tiny sound drivers, they’re used in IEMs Also in mobile phones.
- samstave 4y ago
  >toys/books/greeting-cards that produce sound. What happens to this material when its cast out? Does it become toxic micro particles in our waters, bodies?
  - DrBoring 4y ago
    > Does it become toxic micro particles in our waters, bodies? I think the answer to that question lays somewhere between maybe and probably. I'm curious, what made you bring up the point ? Is micro-particle poisoning a common concern for you. Or perhaps it was it the context of micro-particles being used in the aforementioned products which have short ownership-periods ? I'm not trying to dismiss your concern, I'm just curious why bring it up now. On the topic of shortly-owned-products, I for one have a dislike for cheap plastic beach toys. For example, the retailer Dollar Tree sells plastic sand buckets that break at an amount of force easily exerted by a child. At the beach where I vacation, you can peer into any trashcan and find broken sand toys and foam boogie boards which only break after one day of use.
ryeguy_24 4y ago
Anybody know what the frequency response looks like for this? I assume it can’t generate high decibel sound at very low hz?
julian_sark 4y ago
I had loudspeakers with exposed paper thin components, and it's definitely not cat compatible. So for the home, that's a hard pass.
cestith 4y ago
The scientists and engineers creating this have great intentions. What it will really be used for, I'm afraid, is audio billboards and in-store audio-enabled ad posters. Maybe we'll be lucky and sports bars with TVs at every booth will use them to focus TV audio only to the individual booth.
- MadSudaca 4y ago
  As penitence, they could use the profits to open a fund that rewards people who achieved great things in fields on human endeavor. Let’s say chemistry, physics, literature, activism, etc. A committee would get together on an annual basis to select the nominees and award the prized to the winners. Maybe the ceremony could take place in countries of temperate climate in the northern hemisphere.
- cxcorp 4y ago
  Or coating entire walls and ceilings to track people with ultrasound without them even knowing. Depending on how good the resolution is, maybe even identifying people? > Because the tiny domes are vibrating, rather than the entire film, the loudspeaker has a high enough resonance frequency that it can be used effectively for ultrasound applications, like imaging, Han explains. Ultrasound imaging uses very high frequency sound waves to produce images, and higher frequencies yield better image resolution. > The device could also use ultrasound to detect where a human is standing in a room, just like bats do using echolocation, and then shape the sound waves to follow the person as they move, Bulović says.
DeathArrow 4y ago
This is not the very thin film loudspeaker design. My old Huawei P30 Pro produces sound through screen vibrations. The only novelty is that the film can be attached to most solid surfaces.
etiam 4y ago
"The flexible, thin-film device has the potential to make any surface into a low-power, high-quality audio source" I kind of wish to be wrong here, but doesn't that likely mean it also lends itself well to 'make any surface into a low-power, high-quality audio sensor'?
- 70rd 4y ago
  Kind of reminds me of https://en.m.wikipedia.org/wiki/The_Thing_(listening_device) https://en.m.wikipedia.org/wiki/The_Thing_(listening_device).
  - etiam 4y ago
    Tremendously interesting read. Thank you kindly!
- samatman 4y ago
  This is deeply embedded in the definition of both microphone and speaker. Any given electrical excitation can be either provided or detected by the part which couples the audio signal to the speaker aka microphone, and if this is an exception it is the first of which I am aware. Of course we already have ok mics the size of sesame seeds so, what's your threat model?
  - etiam 4y ago
    That's pretty much in accordance with how I understood the matter then. > Of course we already have ok mics the size of sesame seeds so, what's your threat model? Really hard to tell without a bit more specifics about implementation and adoption I guess, but co-option of ubiquitous consumer technology in the spirit of The Dark Knight (2008) comes to mind. As you strongly hint at, there are ample opportunities for various kinds of unwanted listening already and it's up for debate whether this clever innovation brings anything qualitatively new to that. Large enough quantitative changes can often turn out to be qualitative changes though, and I find the present technology a bit suspect as something that might give certain people ideas about making shitty IoT devices with it and a partially different set of people ideas about getting huge amounts of those gadgets and sticking them in a lot of places where neither mic nor loudspeaker has any business being constantly present (and where currently there are indeed no such devices constantly present, because even people who aren't entirely in their right mind wouldn't pay for it all). By the way, I am as saddened as anyone to see these aspersions cast on a fresh ingenious and exciting innovation. It ought to be that when we get a miniaturized, scalable, much cheaper and more power-efficient way to manipulate energy like this, that per default makes the world a better place. But here we are.
xyzzy123 4y ago
Hn commenters have quickly established that in theory it could be economically viable to talk with nature so we're all good here.
urbandw311er 4y ago
That’s pretty impressive. That said, I’d be very interested to know the frequency response range of this — I wonder how well it reproduces lower frequencies for example.
- falcolas 4y ago
  If the output drops 20db from 10kHz to 1kHz, the bass response is not going to be very good at all.
dickiedyce 4y ago
I'm pretty sure I saw some technology like this in the UK in the late '90s? With prints (pictures) in frames being used as wall-mounted speakers?
bpiche 4y ago
Chevette Washington's cardboard bike with an integrated loudspeaker deterrent from Virtual Light is almost here :D
unholiness 4y ago
It would be interesting to see the gain curve of this speaker. My (limited) experience with piezoelectric speakers is that they resonate at a single frequency very loudly, and are practically silent outside the resonant peak. Perfect for a microwave beeper, but never going to produce audible speech. The "high-quality" descriptor makes it sound like they have produced a reasonably flat gain curve, which seems really significant! But without any explanation I'm skeptical. It may even be as silly as using an unintuitive technical definition of "quality" - in a second order linear system, the "quality" of the gain curve is the ratio of the amplitude at the peak to the input amplitude... The exact opposite of what a reasonable person would consider high-quality sound.
- hinkley 4y ago
  We've seen plenty of examples of people using interesting materials to visualize harmonics on surfaces. Everything from rice to gloop. A given surface can have many resonant frequencies, where volume pitches upward dramatically. That's a lot more than just beeps, but a good deal less than human speech or music. With enough separate speakers you might be able to manage, but old hi-fi sets had 2-3 speakers per channel at most, and you'd probably need many more than that. At some point you'd start to wonder if a phased array were a better option.
  - jasonwatkinspdx 4y ago
    In speaker transducers, normally you're trying to repress any bending modes of the piston. These produce diffractive interference effects, or in some materials "ringing" modes like a bell that are very hard to filter away. The industry standard way for measuring and optimizing this stuff is a laser measuring rig from Kippel. You can find Kippel data for most drivers on the market.
- meatmanek 4y ago
  In the article, they mention that a 25V signal at 1kHz produced 66dBA, while the same 25V signal at 10kHz produced 86dBA. That suggests the curve is not very flat.
- deleted 4y ago
stefanpie 4y ago
Link to the relevant journal article: https://ieeexplore.ieee.org/document/9714188 https://ieeexplore.ieee.org/document/9714188
sandworm101 4y ago
Lol. MIT is in Massachusetts. Bose audio is also in Massachusetts. A stone's throw from MIT is The Electric Boat Company in Connecticut, the people who build all of the Navy's submarines. >>Used this way, the thin-film loudspeaker could provide active noise cancellation in clamorous environments, such as an airplane cockpit, by generating sound of the same amplitude but opposite phase; the two sounds cancel each other out. The flexible device could also be used for immersive entertainment, perhaps by providing three-dimensional audio in a theater or theme park ride. And because it is lightweight and requires such a small amount of power to operate, the device is well-suited for applications on smart devices where battery life is limited. >> thin film of a shaped piezoelectric material that moves when voltage is applied over it, which moves the air above it and generates sound. [As it is solid, it likely can also be structural/load bearing such as to stop noise from propagating between parts.] Maybe that might be used to develop speakers for the next iPhone or VR headset. Or maybe this is the perfect tech for quieting the noisy parts of a submarine. "This work is funded, in part, by..." I wonder which unnamed parties also contributed.
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_Adam 4y ago
66 dB at 1kHz 86 dB at 10kHz (ouch my ears) This is not at all flat and the implementation suggests it has low gain at lower frequencies. Without publishing of a full response curve this seems like nothing more than university PR. Any comment from the authors of the study?
seanp2k2 4y ago
How is this so different from planar loudspeakers which have been around for decades? E.g. https://en.wikipedia.org/wiki/Magnepan https://en.wikipedia.org/wiki/Magnepan
watersb 4y ago
The transducers on my Magnepan speakers are not much thicker, but the driver assemblies are way bigger. https://magnepan.com/products/magnepan-1-7i https://magnepan.com/products/magnepan-1-7i
numpad0 4y ago
Flexible film piezo itself isn’t new, this must be about its structure and manufacturing method. The photo looks a bit like Li-ion pouches, perhaps tech comes from there?
maxutility 4y ago
> Used this way, the thin-film loudspeaker could provide active noise cancellation in clamorous environments, such as an airplane cockpit, by generating sound of the same amplitude but opposite phase; the two sounds cancel each other out. As someone who suffers from “eardrum suck” [0] when using noise canceling headphones, I’d be concerned if the idea of active noise canceling environments caught on. [0] https://www.nytimes.com/wirecutter/blog/how-do-noise-cancelling-headphones-work/amp/ https://www.nytimes.com/wirecutter/blog/how-do-noise-cancell...
dredmorbius 4y ago
Then there was a slight whisper, a sudden spacious whisper of open ambient sound. Every hi-fi set in the world, every radio, every television, every cassette recorder, every woofer, every tweeter, every mid-range drive in the world quietly turned itself on. Every tin can, every dustbin, every window, every car, every wineglass, every sheet of rusty metal became activated as an acoustically perfect sounding board. Before the Earth passed away it was going to be treated to the very ultimate in sound reproduction, the greatest public address system ever built. -- Douglas Adams, The Hitchhiker's Guide to the Galaxy I'd like someone to examine M.I.T.'s granting agencies for Vogon influences. In other news: having used a 13.3" e-ink tablet as my main driver for the past year, I'm finding that the audio quality of that large, flat surface, at least for podcast listening, is surprisingly good. Not the full richness of a large woofer, but definitely not the thin tin of your typical smartphone, or even smaller tablets.

374 points by go_prodev 4y ago

Seems so obvious once described. It doesn’t explain how well the tiny domes reproduce low frequency sound, since they displace very little air.

ptha 4y ago
Yes it would be nice to get a some comparison of fidelity, range etc. It mentions high-quality sound. But it does seem more efficient than traditional speaker designs. From the article: They tested their thin-film loudspeaker by mounting it to a wall 30 centimeters from a microphone to measure the sound pressure level, recorded in decibels. When 25 volts of electricity were passed through the device at 1 kilohertz (a rate of 1,000 cycles per second), the speaker produced high-quality sound at conversational levels of 66 decibels. At 10 kilohertz, the sound pressure level increased to 86 decibels, about the same volume level as city traffic. The energy-efficient device only requires about 100 milliwatts of power per square meter of speaker area. By contrast, an average home speaker might consume more than 1 watt of power to generate similar sound pressure at a comparable distance.
- chrisco255 4y ago
  The article has a video of the speaker playing "We Are the Champions" by Queen. It's clearly muffled quite bit, but damn good quality for a paper thin speaker burning just 100mW.
  - martyvis 4y ago
    Actually it's 100mw per square metre, so maybe that small speaker was only a couple of milliwatts
- dotancohen 4y ago
  Sounds perfect for a cellphone. Imagine theater sound - or even a decent loudspeaker conversation.
- buescher 4y ago
  That's a 10db difference in efficiency, which just means it's an efficient speaker, maybe not as efficient as a good horn-loaded speaker.
- eimrine 4y ago
  > But it does seem more efficient than traditional speaker designs. The numbers you have mentioned do not tell that. I have a pair of 4W speakers which can make impossible any dialogue in a 15m^2 room if working on full loudness. The secret is big but lightweight moving parts (diffusor of big square) and absence of bass.

isoprophlex 4y ago

> To overcome this problem, the MIT team rethought the design of a thin-film loudspeaker. Rather than having the entire material vibrate, their design relies on tiny domes on a thin layer of piezoelectric material which each vibrate individually. These domes, each only a few hair-widths across, are surrounded by spacer layers on the top and bottom of the film that protect them from the mounting surface while still enabling them to vibrate freely. Whoa, does this mean an array of individually addressable micro-speakers becomes feasible? Like pixels in a computer screen, send different signals to each tiny speaker? That would mean craaaazy spatial audio, if I'm not mistaken.

boomlinde 4y ago
It seems like there's no reason for this use case for the speakers to be individually addressable, and that would probably add significant complexity.
- moffkalast 4y ago
  That would be pretty nuts, sending out a digital signal and have a built-in DAC for each emitter. Probably way too much bandwidth for any of the standard busses though.
  - oblio 4y ago
    The thing is, don't we have a ton of higher bandwidth buses already available? I can't imagine the audio interfaces being faster than HDMI 2.0, USB 4/Thunderbolt, DisplayPort 3, etc.
    - moffkalast 4y ago
      I was thinking more in the line of i2c, i2s, spi, uart, since I think all of those that you listed require very extensive circuitry to parse. (At least that's the motherboard makers' excuse to only include like 2 USB 3.0s and 1 USB 3.1 port and like two bazillion 2.0 ports)
  - 4y ago

moffkalast 4y ago

Very cool! Though it looks like it has the same problems DML has, in that it's hard to get good bass out of them. If nothing else it would be quite useful for IoT applications, replacing ol' piezo buzzers, taking up less space and being more efficient.

natly 4y ago

Really cool stuff > Used this way, the thin-film loudspeaker could provide active noise cancellation in clamorous environments, such as an airplane cockpit, by generating sound of the same amplitude but opposite phase; the two sounds cancel each other out. Not mentioned here is that to achieve this you need to track heads in real time (i.e. with a camera) - the phases need to align at just the right spot - which might be worth the creepiness tradeoff or not idk.

olivierduval 4y ago
Actually, it looks more like isolating the whole cockpit (or room) with the "paper" to the noise is cancelled before entering the cockpit. You could imagine a recording studio with 2 sheet of this: - sheet against the wall to cancel the outside sounds coming INTO the recording room - sheet against the previous one (but turn oppositerly) to cancel the sound from the recording room to go outside the room The contact sheet between both would stay fixed
- Applejinx 4y ago
  Neither of those things would work because the objectionable noise is deep into the bass, which this stuff can't do with the excursion limits it's working with.
twayt 4y ago
I wonder what kind of discordant noise it might produce if the heads are misaligned.

danaos 4y ago

Paper: https://ieeexplore.ieee.org/document/9714188 https://ieeexplore.ieee.org/document/9714188

t-3 4y ago

So, this looks like basically a flexible electrostatic speaker? Which means almost no bass and highly directional?

falcolas 4y ago
Not quite, since an electrostatic speaker requires the surrounding layers to be electrically charged to move the diaphragm. This appears to be closer in form to a piezo (or array of piezos) where the diaphragm itself moves under the electric charge.
Applejinx 4y ago
Not exactly. This isn't a dipole, it's expanding and contracting across its whole surface. So, almost no bass (no excursion) and not as directional as if it were a dipole. Electrostatics put out the inverse wave behind them, this is either mounted on a rigid object (no back radiation) or in free air (in-phase back radiation, and front radiation is half as powerful as it would be against an object)

amelius 4y ago

Cool, imagine wall-paper made out of this stuff ... Could it disrupt the hifi speaker market?

deleted 4y ago
[deleted]
Sebb767 4y ago
> Could it disrupt the hifi speaker market? Most likely not. The sound quality will probably be far below what you get with normal speakers at the same price point, not exactly what audiophiles are looking for.

moron4hire 4y ago

If they can make this transparent all the way through, it might be useful for creating tactile interface on capacitive touchscreens.

mlatu 4y ago
oooh, yes that too. but even opaque you could use it for haptics: VR gloves and similar

dsr_ 4y ago

They keep saying "high quality" but the article does not justify that in any way. It's an MIT press release. The major flaw of the article is that it does not link to an actual paper.

cjg 4y ago
It was in another comment: https://ieeexplore.ieee.org/document/9714188 https://ieeexplore.ieee.org/document/9714188
- layer8 4y ago
  Paywalled though.
falcolas 4y ago
> but the article does not justify that in any way. In a way, they did. They said that the 1kHz tone was "high quality", which most likely means it reproduced the waveform they sent fairly accurately. Of course, it's not a complete answer, and I too would appreciate the actual paper. "When 25 volts of electricity were passed through the device at 1 kilohertz (a rate of 1,000 cycles per second), the speaker produced high-quality sound at conversational levels of 66 decibels." Not sure if it matters, but the fact that it's producing ~10x (2^3.333) the sound pressure (which is around 4x louder by human perception) at 10kHz vs 1kHz is vaguely concerning. It would require a fair bit of additional resistance to try and get a "flat" loudness across the spectrum, especially since human hearing is more sensitive at higher frequencies. Absolutely doable, but it means the speaker film can't just be used out of the box.
Applejinx 4y ago
High quality could mean that it produces high efficiency at its optimal frequency, or that it can be cut and bent and shaped any way you want. They're probably not talking about or even understanding 'audio quality' in the sense of 'is this going to replace your Magnepans or electrostatics?'. As designed it will not. It might make for a great tweeter or mid-and-up driver, though. No reason you couldn't put it ON a big ol' flat panel woofer (or whatever suitable shape is best). Then it becomes a coaxial, and maybe there are big wins along that path. If it's light, just sit it ON the bass driver and that does your excursion. The surface layer adds all the mids and highs.

dr_dshiv 4y ago

There are lots of small voice coil speakers that you can attach to a table or window to turn it into a speaker [1]. Anyone know what the advantage of the paper thinness is? [1] search for “surface transducer”

jacquesm 4y ago
I've glued four of those to the soundboard of an elderly Yamaha G2 to give it some interesting capabilities.
- tambourine_man 4y ago
  That sounds (hehe) interesting. Do you have some video or more info to share?
  - jacquesm 4y ago
    Apologies for the crappy playing (this was still very early days): https://www.youtube.com/watch?v=6BqYQdKn0UA https://www.youtube.com/watch?v=6BqYQdKn0UA The original piano of course still works (but can be disabled with a slide) so you can either layer multiple instruments or change instruments altogether (instant organ, for instance). The amp is really tiny, it probably doesn't put out more than 5 W but the soundboard serves as a natural amplifier and with the sustain pedal open the whole thing comes to life. The main use of this feature is to play the 'other' hand while practicing, it sounds a lot more natural when it comes through the soundboard rather than the tinny speakers in the PC. You can use any kind of midi based synth for that, I'm using various synths and Pianoteq on Linux.
    - tambourine_man 4y ago
      That’s very cool, thanks for sharing!
falcolas 4y ago
As I understand it, this can be attached directly to any surface, including completely dead surfaces (for example, a piece of fiberglass/mineral wool insulation), without impacting the sound.

dt2m 4y ago

> When 25 volts of electricity were passed through the device at 1 kilohertz (a rate of 1,000 cycles per second), the speaker produced high-quality sound at conversational levels of 66 decibels. At 10 kilohertz, the sound pressure level increased to 86 decibels Read: Tinny af. Nonetheless, VERY exciting technology. Will be interesting to watch as it matures.

cushychicken 4y ago
Could likely compensate that with digital EQ, though.
- layer8 4y ago
  Bass frequencies are inherently impossible with that kind of physical design. To move enough air at low frequencies, you need more physical depth (higher amplitude).
  - kierenj 4y ago
    Wouldn't the accumulated effect be viable though? I mean, air molecules are tiny, but there are lots of them vibrating in a coordinated way to make bass..
    - layer8 4y ago
      Just compare the surface area and displacement of the actual tiny domes with the surface area and displacement of a bass-capable loudspeaker membrane. If you do the math, I don’t think there’s any chance.
      - im3w1l 4y ago
        Could you get a balanced sound if you cap the volume? Like maybe the domes can't do 60dB of bass, but what about 20?
        deleted 4y ago

vardump 4y ago

Sounds (ahem) a lot like Audio Pixels, from about 10 years ago. I wonder whether anything real ever came out of that? At least looks like they have a web page, https://www.audiopixels.com.au/ https://www.audiopixels.com.au/.

goodmachine 4y ago
Audio Pixels are going down a somewhat different route (MEMs to produce a speaker-on-chip) From the latest shareholders report: "devices were measured and demonstrated to reproduce a near flat frequency response from 100Hz through 50KHz This pioneering achievement for the first time makes it possible for a single device to reproduce crystal clear sound throughout the audible spectrum ‐ without imposing the tradeoffs required by conventional speaker technologies to achieve quality sound through the utilization of separate drivers to reproduce the low, mid, and high frequencies" That said, they've been working on this idea for some time, no indication of when if ever a viable mass product will land

mlatu 4y ago

Also, HAPTICS! i mean, you could use this to make haptic gloves and similar gadgets for VR

layer8 4y ago
I don’t think each dome is individually addressable. The general problem with that is the huge amount of traces (wires) you need to route for individual control. And if all domes emit the same vibrations, you just get a vibrating glove, not fine-grained haptics.
- mlatu 4y ago
  it's a phasearray, therefore you are bound to have some x/y control. also, look at your screen and tell me more about lots of traces.
  - layer8 4y ago
    Screen pixels store their state and are updated in sequence, not simultaneously (hence the “jelly scroll” effect), and only at low-for-sound frequencies (60-240 Hz nowadays).
    - mlatu 4y ago
      ever touched a strung guitarstring? the highest string, 5 or 6. fret: 400Hz im not saying this can just be tailored into haptics AS IS of course you will need to put some work into this, but having hardware like this opens up many possibilities if i were you, i wouldnt just dismiss the idea (just because you cant see how to implement it, doesnt mean noone else wont)
      - layer8 4y ago
        I’m not dismissing the idea, I’m saying that the design presented doesn’t seem to bring us that much closer to solving the actual problems with implementing high-resolution haptics. People tend to severely underestimate the difficulties.

ourmandave 4y ago

Reminds me of Vogons... People of Earth, your attention, please. This is Prostetnic Vogon Jeltz of the Galactic Hyperspace Planning Council. As you will no doubt be aware, the plans for development of the outlying regions of the Galaxy require the building of a hyperspatial express route through your star system. And regrettably, your planet is one of those scheduled for demolition. The process will take slightly less than two of your Earth minutes. Thank you.

pbhjpbhj 4y ago
Wrong thread?
- evilotto 4y ago
  Right thread. Every tin can, every dust bin, every window, every car, every wine glass, every sheet of rusty metal became activated as an acoustically perfect sounding board. Before the Earth passed away it was going to be treated to the very ultimate in sound reproduction, the greatest public address system ever built. But there was no concert, no music, no fanfare, just a simple message.

phasersout 4y ago

Pretty cool, but you still need a big ass subwoofer for the low end..

MrBuddyCasino 4y ago

Transducers are nothing new, and piezo speakers are nothing new. That said, this might improve audio in constrained spaces such as wristwatches, smartphones or laptops, because you can re-use existing larger surfaces. It will probably not replace traditional speakers due to simple physics: sound pressure depends on displacement volume, which means area * excursion. Piezo crystals are not very flexible and have weakness in sound reproduction. They were used in cheap tweeters for some time, but have fallen out of fashion because at higher volumes they start to "scream" in a very unpleasant way. The higher excursion requirements also means they cannot be used for low frequencies. Acoustic short-circuit also means that you cannot just have a thin paper-like loudspeaker, as the waves from the front and the back cancel each other out (this does not apply to wallpapers).

biccboii 4y ago

thomasfl 4y ago

This is a good example of the first principle, made famous recently by Elon Musk. If you identify the problem and common assumptions, you will probably ask yourself if a few vibrating loudspeakers is simply what everybody is doing. Lots of tiny loudspeakers working in unison, could actually produce sound cheaper and better.

JohnJamesRambo 4y ago
Yes it is very Elon-like because unless I’m misunderstanding the article this has been done many times before and has massive drawbacks not mentioned in the press release. https://en.wikipedia.org/wiki/Distributed_mode_loudspeaker https://en.wikipedia.org/wiki/Distributed_mode_loudspeaker You can buy your own for $15 at Parts Express. https://www.parts-express.com/Dayton-Audio-DML25-4-2-Distributed-Mode-Loudspeaker-Transducer-20W-4-Ohm-295-236 https://www.parts-express.com/Dayton-Audio-DML25-4-2-Distrib...
- staindk 4y ago
  Yeah was going to say, this reminded me of this[1] video (series of videos actually, but this is the first in the series). Interesting stuff. [1] https://www.youtube.com/watch?v=zdkyGDqU7xA https://www.youtube.com/watch?v=zdkyGDqU7xA

duckmysick 4y ago

Could this process be reversed to produce paper thin microphones?

ZoomZoomZoom 4y ago

If there's multiple sound sources on a plane, how will it deal with phasing issues, when the distance between opposed points is significant?

DrBoring 4y ago

I wonder if this tech will lead to better quality audio from toys/books/greeting-cards that produce sound. I often wonder if the poor quality in such applications is due to the tiny speaker, or a mixture of the playback hardware and low audio bitrate. > the thin-film loudspeaker could provide active noise cancellation in clamorous environments, such as an airplane cockpit, by generating sound of the same amplitude but opposite phase; the two sounds cancel each other out. What would such an environment sound like? For example, how far would your voice travel when speaking to the person sitting next to you?

tristor 4y ago
> I wonder if this tech will lead to better quality audio from toys/books/greeting-cards that produce sound. Possibly. Eventually. We already have very high quality tiny sound drivers, they’re used in IEMs. They’re expensive though. The quality of the applications you asked about is mostly limited by BOM cost. If this new speaker can get it’s cost down, it seems like a big win especially for places that are space limited in depth.
- 323 4y ago
  > We already have very high quality tiny sound drivers, they’re used in IEMs Also in mobile phones.
samstave 4y ago
>toys/books/greeting-cards that produce sound. What happens to this material when its cast out? Does it become toxic micro particles in our waters, bodies?
- DrBoring 4y ago
  > Does it become toxic micro particles in our waters, bodies? I think the answer to that question lays somewhere between maybe and probably. I'm curious, what made you bring up the point ? Is micro-particle poisoning a common concern for you. Or perhaps it was it the context of micro-particles being used in the aforementioned products which have short ownership-periods ? I'm not trying to dismiss your concern, I'm just curious why bring it up now. On the topic of shortly-owned-products, I for one have a dislike for cheap plastic beach toys. For example, the retailer Dollar Tree sells plastic sand buckets that break at an amount of force easily exerted by a child. At the beach where I vacation, you can peer into any trashcan and find broken sand toys and foam boogie boards which only break after one day of use.

ryeguy_24 4y ago

Anybody know what the frequency response looks like for this? I assume it can’t generate high decibel sound at very low hz?

julian_sark 4y ago

I had loudspeakers with exposed paper thin components, and it's definitely not cat compatible. So for the home, that's a hard pass.

cestith 4y ago

The scientists and engineers creating this have great intentions. What it will really be used for, I'm afraid, is audio billboards and in-store audio-enabled ad posters. Maybe we'll be lucky and sports bars with TVs at every booth will use them to focus TV audio only to the individual booth.

MadSudaca 4y ago
As penitence, they could use the profits to open a fund that rewards people who achieved great things in fields on human endeavor. Let’s say chemistry, physics, literature, activism, etc. A committee would get together on an annual basis to select the nominees and award the prized to the winners. Maybe the ceremony could take place in countries of temperate climate in the northern hemisphere.
cxcorp 4y ago
Or coating entire walls and ceilings to track people with ultrasound without them even knowing. Depending on how good the resolution is, maybe even identifying people? > Because the tiny domes are vibrating, rather than the entire film, the loudspeaker has a high enough resonance frequency that it can be used effectively for ultrasound applications, like imaging, Han explains. Ultrasound imaging uses very high frequency sound waves to produce images, and higher frequencies yield better image resolution. > The device could also use ultrasound to detect where a human is standing in a room, just like bats do using echolocation, and then shape the sound waves to follow the person as they move, Bulović says.

DeathArrow 4y ago

This is not the very thin film loudspeaker design. My old Huawei P30 Pro produces sound through screen vibrations. The only novelty is that the film can be attached to most solid surfaces.

etiam 4y ago

"The flexible, thin-film device has the potential to make any surface into a low-power, high-quality audio source" I kind of wish to be wrong here, but doesn't that likely mean it also lends itself well to 'make any surface into a low-power, high-quality audio sensor'?

70rd 4y ago
Kind of reminds me of https://en.m.wikipedia.org/wiki/The_Thing_(listening_device) https://en.m.wikipedia.org/wiki/The_Thing_(listening_device).
- etiam 4y ago
  Tremendously interesting read. Thank you kindly!
samatman 4y ago
This is deeply embedded in the definition of both microphone and speaker. Any given electrical excitation can be either provided or detected by the part which couples the audio signal to the speaker aka microphone, and if this is an exception it is the first of which I am aware. Of course we already have ok mics the size of sesame seeds so, what's your threat model?
- etiam 4y ago
  That's pretty much in accordance with how I understood the matter then. > Of course we already have ok mics the size of sesame seeds so, what's your threat model? Really hard to tell without a bit more specifics about implementation and adoption I guess, but co-option of ubiquitous consumer technology in the spirit of The Dark Knight (2008) comes to mind. As you strongly hint at, there are ample opportunities for various kinds of unwanted listening already and it's up for debate whether this clever innovation brings anything qualitatively new to that. Large enough quantitative changes can often turn out to be qualitative changes though, and I find the present technology a bit suspect as something that might give certain people ideas about making shitty IoT devices with it and a partially different set of people ideas about getting huge amounts of those gadgets and sticking them in a lot of places where neither mic nor loudspeaker has any business being constantly present (and where currently there are indeed no such devices constantly present, because even people who aren't entirely in their right mind wouldn't pay for it all). By the way, I am as saddened as anyone to see these aspersions cast on a fresh ingenious and exciting innovation. It ought to be that when we get a miniaturized, scalable, much cheaper and more power-efficient way to manipulate energy like this, that per default makes the world a better place. But here we are.

xyzzy123 4y ago

Hn commenters have quickly established that in theory it could be economically viable to talk with nature so we're all good here.

urbandw311er 4y ago

That’s pretty impressive. That said, I’d be very interested to know the frequency response range of this — I wonder how well it reproduces lower frequencies for example.

falcolas 4y ago
If the output drops 20db from 10kHz to 1kHz, the bass response is not going to be very good at all.

dickiedyce 4y ago

I'm pretty sure I saw some technology like this in the UK in the late '90s? With prints (pictures) in frames being used as wall-mounted speakers?

bpiche 4y ago

Chevette Washington's cardboard bike with an integrated loudspeaker deterrent from Virtual Light is almost here :D

unholiness 4y ago

It would be interesting to see the gain curve of this speaker. My (limited) experience with piezoelectric speakers is that they resonate at a single frequency very loudly, and are practically silent outside the resonant peak. Perfect for a microwave beeper, but never going to produce audible speech. The "high-quality" descriptor makes it sound like they have produced a reasonably flat gain curve, which seems really significant! But without any explanation I'm skeptical. It may even be as silly as using an unintuitive technical definition of "quality" - in a second order linear system, the "quality" of the gain curve is the ratio of the amplitude at the peak to the input amplitude... The exact opposite of what a reasonable person would consider high-quality sound.

hinkley 4y ago
We've seen plenty of examples of people using interesting materials to visualize harmonics on surfaces. Everything from rice to gloop. A given surface can have many resonant frequencies, where volume pitches upward dramatically. That's a lot more than just beeps, but a good deal less than human speech or music. With enough separate speakers you might be able to manage, but old hi-fi sets had 2-3 speakers per channel at most, and you'd probably need many more than that. At some point you'd start to wonder if a phased array were a better option.
- jasonwatkinspdx 4y ago
  In speaker transducers, normally you're trying to repress any bending modes of the piston. These produce diffractive interference effects, or in some materials "ringing" modes like a bell that are very hard to filter away. The industry standard way for measuring and optimizing this stuff is a laser measuring rig from Kippel. You can find Kippel data for most drivers on the market.
meatmanek 4y ago
In the article, they mention that a 25V signal at 1kHz produced 66dBA, while the same 25V signal at 10kHz produced 86dBA. That suggests the curve is not very flat.
deleted 4y ago

stefanpie 4y ago

Link to the relevant journal article: https://ieeexplore.ieee.org/document/9714188 https://ieeexplore.ieee.org/document/9714188

sandworm101 4y ago

Lol. MIT is in Massachusetts. Bose audio is also in Massachusetts. A stone's throw from MIT is The Electric Boat Company in Connecticut, the people who build all of the Navy's submarines. >>Used this way, the thin-film loudspeaker could provide active noise cancellation in clamorous environments, such as an airplane cockpit, by generating sound of the same amplitude but opposite phase; the two sounds cancel each other out. The flexible device could also be used for immersive entertainment, perhaps by providing three-dimensional audio in a theater or theme park ride. And because it is lightweight and requires such a small amount of power to operate, the device is well-suited for applications on smart devices where battery life is limited. >> thin film of a shaped piezoelectric material that moves when voltage is applied over it, which moves the air above it and generates sound. [As it is solid, it likely can also be structural/load bearing such as to stop noise from propagating between parts.] Maybe that might be used to develop speakers for the next iPhone or VR headset. Or maybe this is the perfect tech for quieting the noisy parts of a submarine. "This work is funded, in part, by..." I wonder which unnamed parties also contributed.

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_Adam 4y ago

66 dB at 1kHz 86 dB at 10kHz (ouch my ears) This is not at all flat and the implementation suggests it has low gain at lower frequencies. Without publishing of a full response curve this seems like nothing more than university PR. Any comment from the authors of the study?

seanp2k2 4y ago

How is this so different from planar loudspeakers which have been around for decades? E.g. https://en.wikipedia.org/wiki/Magnepan https://en.wikipedia.org/wiki/Magnepan

watersb 4y ago

The transducers on my Magnepan speakers are not much thicker, but the driver assemblies are way bigger. https://magnepan.com/products/magnepan-1-7i https://magnepan.com/products/magnepan-1-7i

numpad0 4y ago

Flexible film piezo itself isn’t new, this must be about its structure and manufacturing method. The photo looks a bit like Li-ion pouches, perhaps tech comes from there?

maxutility 4y ago

> Used this way, the thin-film loudspeaker could provide active noise cancellation in clamorous environments, such as an airplane cockpit, by generating sound of the same amplitude but opposite phase; the two sounds cancel each other out. As someone who suffers from “eardrum suck” [0] when using noise canceling headphones, I’d be concerned if the idea of active noise canceling environments caught on. [0] https://www.nytimes.com/wirecutter/blog/how-do-noise-cancelling-headphones-work/amp/ https://www.nytimes.com/wirecutter/blog/how-do-noise-cancell...

dredmorbius 4y ago

Then there was a slight whisper, a sudden spacious whisper of open ambient sound. Every hi-fi set in the world, every radio, every television, every cassette recorder, every woofer, every tweeter, every mid-range drive in the world quietly turned itself on. Every tin can, every dustbin, every window, every car, every wineglass, every sheet of rusty metal became activated as an acoustically perfect sounding board. Before the Earth passed away it was going to be treated to the very ultimate in sound reproduction, the greatest public address system ever built. -- Douglas Adams, The Hitchhiker's Guide to the Galaxy I'd like someone to examine M.I.T.'s granting agencies for Vogon influences. In other news: having used a 13.3" e-ink tablet as my main driver for the past year, I'm finding that the audio quality of that large, flat surface, at least for podcast listening, is surprisingly good. Not the full richness of a large woofer, but definitely not the thin tin of your typical smartphone, or even smaller tablets.