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.
Horn loaded piezos are common in cheap PA systems (examples: https://www.parts-express.com/search?order=relevance:desc&ke...). They typically work from about 3khz on up, which does involve the upper end of voice. Fidelity isn't great but the things are loud and hard to break for how cheap they are.
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.
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.
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.
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.
> 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.
Directional audio is produced by sound interacting with your ear, so this would not produce spatial audio (unless you would wrap your head in the thin film speaker). What you want is 1 speaker per ear and a software modelling of the HRTF:
https://en.wikipedia.org/wiki/Head-related_transfer_function
That's not what he means, he means using wavefield synthesis which is actually trying to reproduce the physical sound field with speaker arrays, in that case you don't need HRTF processing because your ears are receiving the waves from the actual positions. It can work for a bigger audience in an larger area without wearing headphones and without using head- and position-tracking but it needs lot of loudspeakers for accuracy.
Yeah, instead of 5.1 or 7.1 surround you could have 500.1 or 1000.1 and have soundscapes that are virtually audibly indistinguishable from actually being in the location.
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.
Those are great for spatial audio, true, but they are simply not capable of making sound seem like it is directly in front of me. Some sound comes in through the nose, not a lot obviously, but enough that headphones are dramatically bad at generating sound in front of you.
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
I did. It never sounds like it's in front of me. It's not capable of making sound in such a way as so the sound feels like it is directly in front of me, it's always to the sides or behind me.
Well, I tried with some one else who also didn't feel any spatial effect. I think it depends on whether the binaural recording was done with a head/ear shape similar to yours. So you'll just have to take my word for it that the audio positioning is very accurate. A good HRTF implementation should be calibrated to your head, Sony was talking about that when discussing the PS5's spatial audio: https://youtu.be/ph8LyNIT9sg?t=2979
I do feel it behind me, around my head, but I don't hear it coming from in front of me. It never crosses the threshold to be audibly in front of me because microphones cannot send sound in through my nose or vibrate my face.
The sound can sound the same as if it passed through your nose and face though. The model head they recorded this with had a different nose and face than yours, but you face could also be modelled in an HRTF.
I think op is talking about beamforming when he talks about directional audio, where a large array of speakers would allow you to e.g. send audio in one direction only. The more speakers, the tighter the control.
I don’t think OP was saying that, but you are. A video layer could be built on the gridlines between the speaker domes. Might need to be quite a large screen for the spacing to work out right. Not for high def video, but good for large displays like talking billboards (ugh, actually).
That would be great, but doesn't really need new speaker technology, at the scale of cinema screens - not like you need pixel granularity - just the encoding to support it. When I had a Saturday job at a cinema a couple of the screens had the centre speakers behind them iirc, it just wasn't an individually addressable array.
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'?
> isn't the idea of it that you can put speakers wherever you want and it remixes appropriately?
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
You would also need an IMU in the headphones to modify the phase when the listener adjusts or her head. This is an important part of how we discern forward from behind.
And for some reason using that is a pretty weird experience. I've been so conditioned not to expect it that I actually turn it off to make it feel "natural"
It’s a weird experience, a bit uncanny valley like. I was using while watching video, and it’s somewhat eerie to turn my head and still have the audio from the earphones “pinned” to the screen.
While that's certainly one way to synthesize directional audio, the far more common way is to actually have the audio come from the direction it's supposed to and let your ear do its normal thing to sort it out. Imagine you had an entire room wallpapered in individually addressable tiny speakers, you could actually project sound from any angle. The added benefit being that it would work for more than one person in the room. we've gone from 2.1 audio -> 5.1 -> 7.2 -> atmos 11.2. Why wouldn't we want to go to 50000.2 audio as the next extension?
Atmos is not 11.2!
Home theater Atmos is 12 statically positioned streams, usually 7.1.4 (horizontally_emitting.low_freq.vertically_emitting) and up to 20 dynamically located streams. The audio is then rendered for the speakers configurations. Highest-end decoder can theorically support 24.1.10 but I never saw a decoder support more than 32 channels.
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.
But at thousands of speakers you don't need as much amplification for each wire and considering how these flat speakers are produced, it's not too unlikely that we could eventually be able to embed chips/controllers into then just like we do with current display tech.
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.
Very interesting. While I disagree with the implementation details, you do bring up a great point I completely missed. Embedding electronics into these would be trivial, thus enabling some form of smart communication removing the need for discreet amps and removing most of the labor involved in installation. Man I love HN.
Angular resolution is all very well, but what about spatial resolution? Even from the same compass bearing, a noise coming from a mile away sounds very different than someone whispering in your ear.
Physics/EE students please correct me, I've mostly forgotten this stuff.
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).
While there is certainly a difference between near- and far-field approximations, the short answer is that no, the speakers can be closer than one wavelength together in order to have a steerable far field. In fact, the link you provided has a 1/4 wavelength spaced array as one of its first examples.
You may be confused here because typically it is harder to make lower frequency waves from a single emitter more directional -- but that has more to do with waveguide and aperture geometry.
Looking at the equation for the radiation pattern of the phased array, the angle dependence goes like sin(pi * (N * d/lambda) * sin theta). If N * d (i.e. the size of the array) is much smaller than lambda, there's no interference pattern.
To be more precise, for the radiation pattern to have a null, N * d must be larger than the wavelength.
Yes, but I think that's why you're confused. The distance between the individual speakers would be d, not N*d. Because your original comment was about this spacing, that's what I addressed in my answer.
Obviously a larger effective aperture (either physical or synthetic) would be more effective at beam steering.
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.
A lot of the signal is going to be identical, so a hierarchical distribution with in-place modification based on location would be better than calculating the modification of the sound and sending to thousands of channels.
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)
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.
> 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.
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:
> Modern audio codecs/standards (Dolby Atmos, DTS:X) have moved 'beyond' individual speakers,
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.
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.
Could one use something like this to make a stealth suit thing that does noise cancellation like headphones do to completely mask the noises of the wearer? That would be cool.
The Sony solution actually has subwoofers hidden inside for the bass.
I’m still missing how this paper-thin solution could possibly produce any decent bass.
It absolutely can't. This is a tweeter design. Might be good as that. It's not going to have even enough excursion to do midbass or lower midrange.
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.
> 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.
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).
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..
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.
True, but if the frequency response already drops off that heavily at 1kHz you're going to need some very serious amplification to use it for anything other than speech, even after applying DSP - which I'm guessing defeats the whole purpose of the speaker in the first place.
20db is a lot of compensate (most consumer grade EQ are limited to 12db in either direction, and human ears are more sensitive at higher frequencies). To work with most existing amplifiers, there would likely have to be an in-line circuit to attenuate the voltage at the higher frequencies.
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.
If, by "an order of magnitude", you mean "10db", which works out to be a bit more than 3x the sound pressure required. For comparison's sake, I consider an order of magnitude to be around 10x or more.
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 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'?
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?
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.
Well yes, although around the size of a lentil is where they start sounding acceptable. The characteristics of a microphone will differ when used as a speaker and vice versa, there's a reason music studios don't just use some speakers passively to record sessions.
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).
> 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.
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.
> 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.
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
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.
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.
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.
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.
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
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?
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.
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.
That's not how they're describing it. The "paper" emits sound whether or not it's applied to a wall.
"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.
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)
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.
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?
> 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.
> 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.
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.
---
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?
> that this should be intrinsic to product design at this point
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.
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.
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.
> 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.
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.
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.
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.
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.
I imagine a static, non-flexible screen that you're not supposed to put any pressure on is a very different problem from a flexible, constantly moving glove which is also used to push buttons, grab stuff, etc.
Better to wrap the solid object (button, controller, steering wheel, whatever) in the haptic material than put it in a glove? We do have flexible conductive materials though.
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).
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.
yeah, except for tiny electricaly movable surfaces that can vibrate too... the other haptic gloves that already give high fidelity haptics do it with micro pumps and also tiny bubbles...
i would love to have the time and material to experiment with this... but i dont and wont :shrug:
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?
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.
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.
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.
> 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.
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.
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.
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.
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.