[HN Gopher] MIT researchers develop a paper thin loudspeaker
___________________________________________________________________
MIT researchers develop a paper thin loudspeaker
Author : go_prodev
Score : 328 points
Date : 2022-04-27 09:34 UTC (13 hours ago)
(HTM) web link (news.mit.edu)
(TXT) w3m dump (news.mit.edu)
| DeathArrow wrote:
| 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.
| danaos wrote:
| Paper: https://ieeexplore.ieee.org/document/9714188
| stefanpie wrote:
| Link to the relevant journal article:
| https://ieeexplore.ieee.org/document/9714188
| [deleted]
| t-3 wrote:
| So, this looks like basically a flexible electrostatic speaker?
| Which means almost no bass and highly directional?
| falcolas wrote:
| 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 wrote:
| 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)
| dickiedyce wrote:
| 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?
| mlatu wrote:
| Also, HAPTICS!
|
| i mean, you could use this to make haptic gloves and similar
| gadgets for VR
| layer8 wrote:
| 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 wrote:
| 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.
| KSteffensen wrote:
| 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.
| pbhjpbhj wrote:
| 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.
| layer8 wrote:
| 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 wrote:
| 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 wrote:
| 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.
| DrBoring wrote:
| 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 wrote:
| > 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 wrote:
| > We already have very high quality tiny sound drivers,
| they're used in IEMs
|
| Also in mobile phones.
| samstave wrote:
| > _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 wrote:
| > 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.
| samstave wrote:
| For whatever reason, I have been walking around with this
| _" thats Microplastics in our blood!"_
|
| https://i.imgur.com/2LuS7ix.png
|
| ---
|
| 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?
| etiam wrote:
| "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'?
| fasteddie31003 wrote:
| What if I told you any speaker can be a microphone.
| moron4hire wrote:
| They mention that in the brief, actually
| 70rd wrote:
| Kind of reminds me of
| https://en.m.wikipedia.org/wiki/The_Thing_(listening_device).
| samatman wrote:
| 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?
| [deleted]
| ourmandave wrote:
| 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 wrote:
| Wrong thread?
| evilotto wrote:
| 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._
| moron4hire wrote:
| If they can make this transparent all the way through, it might
| be useful for creating tactile interface on capacitive
| touchscreens.
| mlatu wrote:
| oooh, yes that too. but even opaque you could use it for
| haptics: VR gloves and similar
| Kaibeezy wrote:
| 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 wrote:
| 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._
| dotancohen wrote:
| Sounds perfect for a cellphone. Imagine theater sound - or
| even a decent loudspeaker conversation.
| buescher wrote:
| 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 wrote:
| > 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.
| chrisco255 wrote:
| 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 wrote:
| Actually it's 100mw per square metre, so maybe that small
| speaker was only a couple of milliwatts
| amelius wrote:
| Cool, imagine wall-paper made out of this stuff ...
|
| Could it disrupt the hifi speaker market?
| [deleted]
| Sebb767 wrote:
| > 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.
| bpiche wrote:
| Chevette Washington's cardboard bike with an integrated
| loudspeaker deterrent from Virtual Light is almost here :D
| phasersout wrote:
| Pretty cool, but you still need a big ass subwoofer for the low
| end..
| MrBuddyCasino wrote:
| 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 wrote:
| ryeguy_24 wrote:
| Anybody know what the frequency response looks like for this? I
| assume it can't generate high decibel sound at very low hz?
| thomasfl wrote:
| 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 wrote:
| 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
|
| You can buy your own for $15 at Parts Express.
|
| https://www.parts-express.com/Dayton-Audio-DML25-4-2-Distrib...
| staindk wrote:
| 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
| cestith wrote:
| 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.
| cxcorp wrote:
| 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, Bulovic says.
| MadSudaca wrote:
| 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.
| unholiness wrote:
| 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 wrote:
| 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 wrote:
| 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.
| jasonwatkinspdx wrote:
| 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.
| [deleted]
| meatmanek wrote:
| 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.
| duckmysick wrote:
| Could this process be reversed to produce paper thin microphones?
| urbandw311er wrote:
| 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 wrote:
| If the output drops _20db_ from 10kHz to 1kHz, the bass
| response is not going to be very good at all.
| dsr_ wrote:
| 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.
| falcolas wrote:
| > 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 wrote:
| 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.
| cjg wrote:
| It was in another comment:
| https://ieeexplore.ieee.org/document/9714188
| layer8 wrote:
| Paywalled though.
| dr_dshiv wrote:
| 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"
| falcolas wrote:
| 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.
| dr_dshiv wrote:
| I doubt that! I thought it was using the wall as a resonator.
| falcolas wrote:
| 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.
| jacquesm wrote:
| I've glued four of those to the soundboard of an elderly Yamaha
| G2 to give it some interesting capabilities.
| tambourine_man wrote:
| That sounds (hehe) interesting. Do you have some video or
| more info to share?
| jacquesm wrote:
| Apologies for the crappy playing (this was still very early
| days):
|
| 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 wrote:
| That's very cool, thanks for sharing!
| seanp2k2 wrote:
| How is this so different from planar loudspeakers which have been
| around for decades? E.g. https://en.wikipedia.org/wiki/Magnepan
| isoprophlex wrote:
| > 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.
| traceroute66 wrote:
| > To overcome this problem, the MIT team rethought the design
| of a thin-film loudspeaker.
|
| 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.
| tigershark wrote:
| 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.
| Applejinx wrote:
| 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.
| [deleted]
| WithinReason wrote:
| 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
| jakemoshenko wrote:
| 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?
| nick__m wrote:
| 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.
| klyrs wrote:
| Playing with phase, I imagine that gangs of speakers could
| be used to produce bass as well. Don't need to stop at
| x.2...
| tragictrash wrote:
| That would require a lot of wire and a lot of amplifiers. I
| bet we'll see an installation or two of the proposed design
| for proving it can be done.
|
| 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.
| amlib wrote:
| 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.
| tragictrash wrote:
| 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.
| unlikelymordant wrote:
| 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.
| 0cVlTeIATBs wrote:
| I think OP means e.g. a video call where each person's
| voice is played back from where their mouth is displayed on
| screen.
| Kaibeezy wrote:
| 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).
| tetris11 wrote:
| urgh actually, indeed
| dtx1 wrote:
| Or as a Center Speaker in a cinema setup where the voice
| comes not from "the middle" but out the mouth of an actor
| OJFord wrote:
| 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'?
| dtx1 wrote:
| > 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
| OJFord wrote:
| Oh, ok, I see, thanks for the correction.
| causi wrote:
| If you put headphones on you could do that with software
| without needing special speakers.
| the__alchemist wrote:
| 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.
| panda88888 wrote:
| Apple already does this via spatial audio for AirPod pro.
| airstrike wrote:
| 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"
| spyder wrote:
| 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.
|
| https://en.wikipedia.org/wiki/Wave_field_synthesis
|
| http://www.eliasmerino.com/structural-wfs.html
|
| https://audioxpress.com/news/holoplot-launches-wavefield-
| syn...
| BizarroLand wrote:
| 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.
| WithinReason wrote:
| For VR you could just use a pair of headphones with HRTF.
| This is what that can sound like:
|
| https://www.youtube.com/watch?v=WYdIidUIbAs
| extrememacaroni wrote:
| 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.
| eternauta3k wrote:
| 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).
|
| If you want to understand this, look into
| https://en.wikipedia.org/wiki/Phased_array
| sandpaper26 wrote:
| 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.
| eternauta3k wrote:
| 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.
| sandpaper26 wrote:
| 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.
| boomlinde wrote:
| 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.
| voxadam wrote:
| Maybe you could do something like Holoplot[1] does with their
| full size beamforming speakers.
|
| [1] https://holoplot.com/technology/
| throw0101a wrote:
| > _speakers to be individually addressable_
|
| 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/obje
| c...
|
| > _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)#DT
| S...
|
| 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...
| oblio wrote:
| To a complete noob such as myself, is this somewhat the
| equivalent of 3D graphics and lighting or even stuff like
| raytracing?
|
| After all, 3D graphics create objects and then model their
| interaction with the world.
| Shared404 wrote:
| > or even stuff like raytracing?
|
| 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.
| boomlinde wrote:
| _> 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.
| moffkalast wrote:
| 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.
| boomlinde wrote:
| As an example, a thousand channels of 16-bit samples at 48
| kHz adds up to 768 Mbits/s, which is well within USB3
| bandwidth many times over.
|
| 1000 channels is a rather small array, though. 5000 is
| still not too much.
| robbedpeter wrote:
| 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.
| oblio wrote:
| 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.
| sandworm101 wrote:
| 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.
| xyzzy123 wrote:
| Hn commenters have quickly established that in theory it could be
| economically viable to talk with nature so we're all good here.
| julian_sark wrote:
| I had loudspeakers with exposed paper thin components, and it's
| definitely not cat compatible. So for the home, that's a hard
| pass.
| dt2m wrote:
| > 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.
| samstave wrote:
| Imagine audio way-finding embedded into the paint. THen see if
| yu can place other sensors behind this material as well.
| samstave wrote:
| OK, so apparently one doesnt like this, so let me re-phrase:
|
| 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?
| cushychicken wrote:
| Could likely compensate that with digital EQ, though.
| layer8 wrote:
| 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 wrote:
| 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 wrote:
| 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 wrote:
| 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]
| layer8 wrote:
| Maybe, but then you lose the power efficiency benefit of
| this particular technology.
| cushychicken wrote:
| So what? The peaking is at 10kHz. Way outside of bass
| range.
| falcolas wrote:
| 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.
| dt2m wrote:
| 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.
| vardump wrote:
| 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/.
| goodmachine wrote:
| 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
| moffkalast wrote:
| 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 wrote:
| 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.
| twayt wrote:
| I wonder what kind of discordant noise it might produce if the
| heads are misaligned.
| olivierduval wrote:
| 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 wrote:
| 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.
| ZoomZoomZoom wrote:
| If there's multiple sound sources on a plane, how will it deal
| with phasing issues, when the distance between opposed points is
| significant?
| _Adam wrote:
| 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?
___________________________________________________________________
(page generated 2022-04-27 23:01 UTC)