MIT researchers develop a paper thin loudspeaker
news.mit.edu
news.mit.edu
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.
No one in acoustics calls Q "quality" really. It's just "q" or people talk about underdamped vs overdamped, etc. If quality comes up, it's usually in the context of lower q designs being higher fidelity (eg, a subwoofer that's ~0.707 vs one that's say 1.2).
What's most interesting about this new transducer is that it's physically thin, but acts as a monopole driver. That's cool and unique.
They'll have to make some variations to dial in just how the geometry affects the response.
Also, this driver as is would beam significant when made as large as some of the examples they talk about. But that's probably ok as the output is low enough you'd want to be in the near field anyhow.
Edit Add;
search: >books:'Speaker Design'< @DDG : <https://html.duckduckgo.com/html/?q=books:'Speaker Design'>
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.
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.
https://en.wikipedia.org/wiki/Wave_field_synthesis
http://www.eliasmerino.com/structural-wfs.html
https://audioxpress.com/news/holoplot-launches-wavefield-syn...
Maybe overkill for movies but for VR immersion that could be fantastic, especially if the modules could be rigged to use Bluetooth 5.0 so that they would only need to be paired to your computer and mapped out in software the way multiple monitors are mapped out in windows.
Plus, given enough calculation and precision, you could create areas that are nearly sonically separated from each other using wave cancellation, and as people move through the space it would change the sonic characteristics of the space and create new vibes.
There's a lot of untapped awesomeness in the audio world, we just need to tools to craft them
Maybe other people feel it, but I do not.
Having said that, I suppose Atmos already implicitly supports it, isn't the idea of it that you can put speakers wherever you want and it remixes appropriately? So if your recording was sufficiently granular that dialogue isn't just all vaguely 'at the front' it could already split between say five (corners & middle) 'centres'?
No, Atmos has some tolerance for speaker placement but the general positions are somewhat strict (i.e. 1 Front Center, 2 Stereo Fronts, ...). The idea of Atmos is that given a correct sound setup, a sound can be positioned as an Object in 3d Space within the sound bubble. And that only works to a certain degree. If you want a strong 3D sound effect, the Object pretty much needs to be moving (bullets swishing beside your ear). Static Objects are still somewhat restricted to the edges of the bubble or at least i can hear the 3d effect breakdown when static objects are placed in 3d space as opposed to moving objects
My receiver has 13 outputs (11 amplified, 2 sub at line level) but I use a 5.1.2 configuration, in a relatively small listening room, and I don't know where I could add more speakers without rebuilding the walls and the ceiling.
Still, I bet most spatial audio systems will use software and fewer drivers ( potentially these drivers) to create the intended effect.
It just costs too much to wire all them up.
With that setup you could encode hundreds of channels in a single wire and each embedded controller would be responsible do decode it's addressed channel(s) to send to it's respective "speaker(s)". If the signal produced isn't high enough, you may also add in some small amplification stage in the embedded chip.
Assuming the speaker is many wavelengths away (in the "far field"), the distance between individual speakers needs to be larger (comparable with the wavelength) to make a difference in the radiation pattern in the far field. Speakers which are closer together only make a difference in the near field (meaning the listener is within a few wavelengths of the array).
If you want to understand this, look into https://en.wikipedia.org/wiki/Phased_array
To be more precise, for the radiation pattern to have a null, N * d must be larger than the wavelength.
Obviously a larger effective aperture (either physical or synthetic) would be more effective at beam steering.
1000 channels is a rather small array, though. 5000 is still not too much.
I can't imagine the audio interfaces being faster than HDMI 2.0, USB 4/Thunderbolt, DisplayPort 3, etc.
Modern audio codecs/standards (Dolby Atmos, DTS:X) have moved 'beyond' individual speakers, and are now using object-based sound:
> Audio becomes an object when it is accompanied by metadata that describes its existence, position and function. An audio object can, therefore, be the sound of a bee flying over your head, the crowd noise, commentary to a sporting event in any language. All this remains fully adjustable on the consumer’s end to their specific listening environment, needs and liking, regardless of the device.
* https://www.thebroadcastbridge.com/content/entry/16347/objec...
> Think about this: imagine the sound of a race car speeding around a track. You can see the car approaching in the distance, off on the right side of the screen. As it gets closer, it gets louder and zooms across the screen from right to left, with the resulting Doppler shift of the sound as it goes past you. It screams off the left edge of the screen and continues down the left wall until it disappears into the distance behind you.
> A sound designer could, in theory, pan this sound carefully from the Right speaker, through the Center speaker, to the Left speaker, and on down to the Left side surround and the Left rear surround before it faded out entirely. That would be the channel-based way of thinking about the task at hand.
> Alternatively, the same designer could associate the sound of that race car with locations (coordinates) that move smoothly across the front of the room and then down the left side of the room. It is the same sound, but now with metadata telling the playback system where it should be from one moment to the next. […]
> The second, object-oriented way, is scalable. It doesn’t care how many speakers you have in your room because it is not referencing a specific speaker – just relative locations. Importantly, these locations can include the space above you and around you, enclosing you in a “bubble” of sound.
* https://www.trinnov.com/en/blog/posts/what-is-immersive-soun...
* https://en.wikipedia.org/wiki/Dolby_Atmos
* https://en.wikipedia.org/wiki/DTS_(sound_system_company)#DTS...
Given the (x, y, x) co-ordinates of an audio signal/object, the codec algorithm figures out which speaker(s) should get what signal: if the system only has two speakers then you'll generally only have stereo, if you have a 7.1.4 setup (four overhead / in-ceiling speakers) it will probably be more immersive:
* https://www.dolby.com/about/support/guide/speaker-setup-guid...
* https://www.dolby.com/about/support/guide/speaker-setup-guid...
What you're describing is representational. You still need individually controlled speakers to position audio in the room according to the positional metadata. The question of representation really isn't relevant to the question I answered, nor is it to my answer, but it's an interesting topic.
> Given the (x, y, x) co-ordinates of an audio signal/object, the codec algorithm figures out which speaker(s) should get what signal
...and for the signals to be distributed accordingly, you need to be able to address each speaker individually.
In the domain of representing positional audio, this is also nothing new. No one mixes surround sound in terms of speakers, and that has been the case for decades. No one would manually pan a sound "carefully from the Right speaker, through the Center speaker, to the Left speaker, and on down to the Left side surround and the Left rear surround before it faded out entirely". What object-based codecs bring to the table is that the positional representation is encoded in the data stream rather than mixed down to per-speaker audio streams during production, which means that the distribution and filtering can be tailored for each setup individually.
After all, 3D graphics create objects and then model their interaction with the world.
Someone correct me if I'm remembering wrong, "sound raytraycing" was a feature in the game Thief if you had a compatible sound card, right?
I (also not sme) think the best graphics analogy would be holograms in Star Wars - object is at point-in-room, and you can hear/view it there.
The big tech here is the ability to spacially position the audio in the physical space the speakers sit in, by automatically mixing it between the speakers.
Sorry if I misunderstood the question, or a smarter person answered while I was typing.
I wonder if the team has seen Sony's OLED TV's with Acoustic Surface ?
The screen itself is used as a large speaker, and its surprisingly good.
Mind you if the description is correct, to hear it properly they need to adhere it to a physical object. Having it dangling in free air like that means it's a lobed omnidirectional radiator: opposite of a dipole, it's putting out the same signal to either side across the whole plane, and the edges aren't putting out anything, and the range isn't low enough to hear it side-on very well: highs are directional.
This is why when he curves it you hear treble louder: it's making a little dish aimed at the mic (roughly). You could easily make a tweeter for 'head in a vice imaging' where the curvature is such that it's aimed only at the ear position, for less near reflections off walls. As described, you'd always want to back it with a physical object.
In a large enough area it's a midrange driver with very high peak output in the highs. You could curve it the opposite direction to make the mids slightly dominate over the highs: slight off-axis will attenuate highs a little more than mids, and the differences in hearing position across the curved surface (it's a smooth radiator without any specific driving points) will cause higher frequencies to cancel, again reinforcing lower frequency stuff.
Read: Tinny af.
Nonetheless, VERY exciting technology. Will be interesting to watch as it matures.
What area in CM(2) is good for fidelity, and to really push the question, how easily does this become a mic?
So imagine a sensor the size of a dual gang outlet (https://i.imgur.com/8bAhAnr.jpeg) which can track a TON of things?
Now imagine that face-plate being coated in this material?
12dB in either direction was standard issue in, like, the 70s. Plenty of modern eqs can do almost 40dB of damping.
Human ears are, in fact, way less sensitive at higher frequencies. Review the Fletcher Munson curve. Takes an order of magnitude more power to generate same perceived loudness at 10kHz as 1kHz.
This is a piezo speaker, which typically have really different driving requirements than a typical transducer, so it's probably not suited to work with most existing amplifiers anyway. Getting the EQ right is table stakes for getting this production ready.
Source: me, I have about a decade of experience in consumer audio.
Exaggerations aside, I could very well be wrong about that part - I was basing my observation off the response curve of reference headphones, which all fall off drastically starting a bit before 10kHz. But since they sound the same throughout the frequencies, I inferred that hearing is more sensitive slightly before 10kHz, since even age-degraded hearing can go above the 14kHz range.
> 12dB in either direction was standard issue in, like, the 70s.
Look at the EQ provided with your phone's audio application. 12 dB plus and minus. Look at the EQ on your computer. Unless you're using custom software, it's more-than-likely going to be 12db (Spotify, iTunes, WMP, etc.).
40dB of dampening is custom hardware your average sound bar won't have. That your average consumer-grade home theater system won't have. That even a quality headphone amp/dac won't offer.
> Getting the EQ right is table stakes for getting this production ready.
Here we agree, as I pointed out in the post you're responding to.
The Decibel : https://en.wikipedia.org/wiki/Decibel
The Decibel Watt aka dBW : https://en.wikipedia.org/wiki/Decibel_watt
Sound Pressure : https://en.wikipedia.org/wiki/Sound_pressure
Sound Level Meter aka Sound Pressure Level Meter (SPL) : https://en.wikipedia.org/wiki/Sound_level_meter
Equal-Loudness Contour : https://en.wikipedia.org/wiki/Equal-loudness_contour
If you are going to break the Context tree, please include the replied reference post;
ie. >the Fletcher Munson curve< : > https://news.ycombinator.com/item?id=31215503 < Added reference. Thanks
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'?
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?
> 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.
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).
It's an MIT press release. The major flaw of the article is that it does not link to an actual paper.
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.
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.
> 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.
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
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.
> 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.
At least looks like they have a web page, https://www.audiopixels.com.au/.
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
[1] search for “surface transducer”
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.
"The hand-sized loudspeaker the team demonstrated ... can generate high-quality sound no matter what surface the film is bonded to."
It is, as I understand it from the article, a bunch of 3-4nm sized piezoelectric elements in an array, all powered concurrently.
"... 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."
If the vibrating elements are decoupled from the surface, the surface won't act as a resonator for it (at least, not as the primary resonator, as it would with a transducer). The vibrating elements are moving the air directly.
If nothing else it would be quite useful for IoT applications, replacing ol' piezo buzzers, taking up less space and being more efficient.
> 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?
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.
Also in mobile phones.
What happens to this material when its cast out? 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.
https://i.imgur.com/2LuS7ix.png
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But literally, I think that this should be intrinsic to product design at this point, and anything short is criminal....
One should be responsible to think about product lifecycle as it pertains to the environment.
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I have always been anti-pollution in every sense... and its getting our of fn control - and politicians should be melted at the stake (pour molten plastic over them) - as they have failed to hold ZERO petroleum (plastics) producing company TRULY accountable for anything.
If you disagree, show me positive ACTUAL meaningful progress in curtailing human waste?
I don't think it is feasible to engineer products in a way which optimizes their disposal. Certainly that is not something most consumers are concerned with. Surely if it were, there would be fewer manufacturers selling junk fall-apart products.
> Politicians should be melted at the stake (pour molten plastic over them) - as they have failed to hold ZERO petroleum (plastics) producing company TRULY accountable for anything.
I find it unlikely that many politicians are interested in holding to account any plastics manufacturer for the pollution caused by their products. But, for exactly what should they be held accountable ?
And, on whose onus the proper disposal of plastics products? I say it's the consumer, not the manufacturer.
>>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.
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.
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-cancell...
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.
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.
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?
i mean, you could use this to make haptic gloves and similar gadgets for VR
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)
i would love to have the time and material to experiment with this... but i dont and wont :shrug:
The only novelty is that the film can be attached to most solid surfaces.
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.
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.
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.
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-Distrib...