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Technology

British Firm Develops Invisible Speakers 82

Posted by sengan from the vorgon-sound-system dept.
somebody else writes "According to this AP article on Yahoo!, a British firm has developed a loudspeaker that can be heard, but not seen. It uses glass or plexiglass panels that emit sound through subtle vibrations. See-through speakers should enable better sound on laptop computers, and use a car windshield/windscreen to double as a stereo speaker"
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British Firm Develops Invisible Speakers More

British Firm Develops Invisible Speakers

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  • This reminds me of The Hitchhikers Guide To The Galaxy, where the Vorgons turned all glass and metal into loudspeakers.
  • is glass invisible? Ooooh, you mean _transparent_.
  • since the glass would be vibrating both ways, using a window as a speaker means you'd be sending sound out as well as in. Half your power wasted.


    Think I'll stick with traditional technology.

  • Posted by Rob Butler:

    "Transparent speakers" being revolutionary? I don't think so. This is just some company making a big media splash about electro-static speakers, that have been around since the 1940's. In fact, I have three "transparent" speakers at home already, the Martin Logan Cinema center speaker, and the reQuest mains.
  • Posted by smartass:

    Actually it's sortof been done. They are electrostatic, or Magna-planar speakers. One of the largest manu. is Martin Logan, http://www.martinlogan.com . Basically it's the same concept, but with a sheet of metal.

  • Heh (Score:1)

    by Da Unicorn ( 941 )
    Seems like Klipsch did this years ago with mylar or something ?? My memory being what it is.. I could be totally wrong.
  • I don't believe that would work without disturbing the screen image. The user is looking straight at it, and all the vibration would be disturbing to watch.
  • Talk about timing.

    I was lucky enough to goto a seminar given this morning by Dr. Graham Bank, one of the chief design engineers at NXT, (one of the few perks of doing an Msc at Essex university in the UK).




    The speakers are seriously impressive. He showed us a laptop that had a pair of the DML speakers as slideout panels behind the LCD. They were about 4 inches by 4 inches and the quality of sound is MUCH better than the usual tinny little things that are usually tacked onto laptops. You could play Quake/QuakeII and actually enjoy the sounds for a change.


    They're basically a honeycomb like panel which resonates in a random manner when excited at one of it's modal points. Due to the resonance being uncorrelated the resonance of the panel doesn't effect the load the amplifier sees. It's dispersion characteristics are also a damn sight better than the normal cone. I'd expect them to take off in the home theatre area most, but you never know, car windscreens.....




    Just my 2p worth


    Iggy
  • I've seen 3d dispersion graphs for these speakers at 500, 1000 and 7000 Hz, and they produce an almost spherical dispersion characteristic at all those frequencies. At the higher frequencies it's not quite as perfect as lower frequencies, but non the less, much better than conventional pistonic moving coil and even electrostatic speakers. You still get a small amount of cancellation at the edges of the panel but not too much.


    How do i know this, cos' i've seen them working and talked to the designer, Dr. Graham Bank. I saw a DML panel of about the same size as a 19" monitor reproduce a music signal over a roughly 200Hz to 20KHz bandwidth. Pretty impressive if you ask me.

  • That would sound terrible when I'm doing 120mph...
    --
  • Wouldn't have bought the Jag if I didn't want to do 120 ;-)

    Hmm - it'd be interesting as a noise reducer though...
    --
  • You'd need a second layer, 180' out of phase, to cancel out the distortions. But that'd cancel out the sound.

  • Besides... (Score:1)

    by jd ( 1658 )
    ...Tomorrow's World demonstrated some =much= geekier, mugh higher-quality speakers a number of years ago. (It involved setting up a controlled, miniature thunderstorm. :) The speakers they showed could generate perfect, pure tones, over almost any range. Nice stuff. I suspect they were a tad noisy in the radio spectrum, though.
  • How many large-scale book-burnings have you seen lately? (and a couple of fundamentalists out in Texas doesn't count..)

    Daniel
  • Remember the Vogon construction fleet? Perfect sound from every wineglass, windowpane, and pretty well anything that could be used as a sound board.
    Now they need to figure out how to do this with rusty tin cans, and when the Vogons, come visiting, we can outshout them!
  • Wow! Now my 21" monitor should rock!
  • See-through speakers could, in theory, be as large as movie screens and small enough to fit on a business card. Refinements in the technology might even enable a car windshield to double as a stereo speaker.

    Sounds nice.... BUT!

    Under close magnification, the speaker surface resembles a three-dimensional map of mountainous terrain, with each peak punching the air to help
    create sound waves.

    Imagine getting in a car accident, and having your face smash into the three-dimensional map of a mountainous terrain. It may be small, but it's probably enough to cause some damage.
  • They never really said how much of a magnification was needed for that. I took it as being enough to make the glass feel rough, but still be able to see through it fine.

    As an upside... I guess i would be cool to be able to say "I got into a car accident, and flew through the speaker."
  • I met a few people in Lawrence, Kansas who used to work for Martin-Logan who made some of these. [martinlogan.com] They are speakers that use a near-zero mass driving element controlled by static electricity. The theory is: mass of the element is negligable, an almost perfect, pure, rich sound can be replicated. The disadvantage is that the amplifier has to be at least a half a kilowatt for accurate reproductions.

    I have heard from these membrane speakers and it is a real experience. They are costly due to the voltage multipliers, the rack mounted amplifier, and the source of the music.

    But its worth it if you have the money and the space to put these works of art in your living room. If you are tired of the sound heavy diaphrams of speakers produce and tweaters seem to resonate harmonics, these are a godsend.

  • Sorry, not for me. I would still prefer my JBL studio monitors.

  • Heh (Score:1)

    by RISCy ( 5493 )
    ESL's Electrostatic Loudspeakers. Been around for a while, and can perfeclty reproduce a square wave. You cant see through them though.
    ---------------------------------
  • Directionality goes up as frequency goes up, no matter what the source, for sound waves as well as electromagnetic/electrostatic; i.e., radio,TV,microwave,et cetera. The higher the frequency the shorter the wavelength, the shorter the wavelength, the less the waves are able to "wrap around" obstacles so the chair that blocks your tweeter doesn't stop your woofer and the pine tree that blocks a UHF station doesn't block a VHF station.

  • In a former life I used to sell audio. The first half of the job was "de-educating" potential customers from the misconceptions they get from the ads. ("Listen to the 3" speaker fed by a 1 transistor damn near "Class C" amplifier in this $50 portable TV, and we'll show you how much better this $1000 system sounds than this $500 system!")

  • There was an article in one of the Popular Mechanics-type magazines in the mid '60s about speakers that were basically two electrodes conducting across the separation between them because that air was ionized because it was the middle of a gas jet flame! Seriously! Supposed to have sounded pretty good.
    About "72 to '75 Fisher offered flat panel speakers, some of which looked like pictures (oil painting, not photograph) in a frame and were designed to be hung on the wall. I used to sell them, they weren't bad for the money if you allowed for a 10-15% "novelty factor" in the price and cut them a little slack for their space saving virtue. Fisher made speakers for lots of other companies in those days. About that same time another company (Magnaplanar?) was also offering flat speakers in two or three rectangular sizes. They looked like flat white pieces of plastic, at least in the magazine ads, never saw them in person.
  • Instead of buying an anti-glare filter for your CRT-type monitor_and_buying speakers to hang of off the sides of it just get one thig that's both!

  • Correct me if I'm wrong (and I'm *sure* someone will) but haven't these been around for awhile? I seem to recall seeing these in hi-fi shops around town.

  • If you hit something hard enough to cause you to fly out of your seat and smash your face into the windshield, a three dimensional wave in the glass is the least of your worries. Come to think of it, hitting the glass with your face would set up bigger vibrations than this thing could. Of course if you would just wear your seatbelt, you won't hit the glass at all, making this all a moot point...
  • I'm not so sure about that. It all depends on the rate of vibrations in the screen, and wether that is percievable by the human eye. By the sound of the technical specifications of this thing, I'd say that visual interference from the vibrations would be very small, for all purposes, inconsequential.

    -Laxative
  • This is really starting to feel like Fahrenheight 451. Anyone know what I'm talking about? Remember 'The family'? With flat screen technologies coming out, and now flat-surface sound - you can build whole "entertainment rooms", for psuedo-3d viewing. There are also bud-earphones (compare to "sheashell" in Fahr.541), and less and less people are reading books nowadays. Robotic dog? they have a robotic fish now, how long before other animals start showing up? And finally, the culture we live in is starting to become more and more oversensitive. All people bow to the god of political correctness. The similarities are UNCANNY.

    -Laxitive
  • Fahrenheight 451 had nothing to do with book burning. Book burning was a plot element to illustrate bradbury's point. The point was, individual free thought and the right to criticize (part of the right to free speech) was supressed for the sake of "non-offensiveness". The reason books were being burned was because any book offended somebody - had a point of view that some minority or majority group disagreed with. The book was about the abolition of diversity to perserve the 'unity' of a community.

    -Laxative
  • hmm...turn all my windows and windshield in my car into speakers....
  • this has already been done, as far as i know. it appeared in Popular Mechanics almost a year back, and there's already speakers available that implement this "flat" technology (Benwin). The sound quality is hardly on par with traditional drum/magnet speakers, from what I've heard however.
  • The way I read the article, this "mountainous terrain" is created by the vibrations of the plexiglass, rather than the plexiglass being manufactured with a rough surface. Also, I doubt that vibrations "invisible to the human eye" could possibly do the kind of damage you're talking about.
  • Just because the distortions are invisible to the naked eye doesn't mean the effects will be. The distortions will effectively be many small concave/convex lenses moving around with the sound. It might not be enough to show, but then again it might bother some people - 60Hz refresh is fine for some people, but even 76Hz isn't enough for some. I'd want to see an eyestrain study done on monitors with this technology before I used it. Also, even small vibrations on a fairly continuous basis could be bad juju for electronics...most motherboards I've seen aren't really that vibrationally stable. Any surface mount components could potentially be very sensitive to these things - I've always wondered about the Intel flash chips that come in a microBGA package with "wings" that stick out nearly a centimeter past the last pin/pad...I'd think they'd resonate at some frequency. Oops...getting off topic. That'll do, I guess.

  • From the article

    NXT says its see-through speakers have a wider frequency than conventional ones, giving them a deeper bass and a less tinny sound. And they project sound in all directions at once, making it unnecessary, for example, that an audiophile face a stereo speaker to hear music at its clearest.

    This makes me a bit skeptical. Even if they project in all directions at once (unlikely with a flat panel?), they still must have a source (esp. at higher frequencies). If they still have a source, then one still must face the speaker for the proper image. By analogy, if I wave my hand in a pool of water, the ripples will project in all directions at once, but my hand is still the one creating the waves.

    Also, to get any decent low-end response, the panel would have to be quite large. All they say is "wider frequency," which in audio terms means jack.

    Jason Dufair
    "Those who know don't have the words to tell

  • well, first off on the volume thing, if the surface area of one of these is substantially larger than the surface area of a conventional speaker, wouldnt it add up to the same volume with less vibration ? or am i wrong. like 1000 smaller speakers on low volume adding up to one loud one ?

    second. who's to say they'd put the speaker as the viewing surface for a tv or whatever ? seeing as it just cuts down weight and size, they could just make it the cover over the LED's for the tv, or the panel on the side... of course, they'd have done that with the opaque ones by now i'm sure.

    then again... wouldnt that be trippy ? :) trails to the bass of a video ? add a little visual kick to the trex of jurrassic park.

    ElecMoHwk

  • Ah, embedded information....

    But of course we already know some people are very classified/restricted access, so it wouldn't hurt for this to be done.

    On the other hand, I can see Get Smart!'s 'cone of silence' being done with this...

    AS
    AS
  • I would actually argue those distortions already occur in the plateglass because of road noise when you travel on a freeway, and if you aren't bothered by that, I don't know that you would be bothered by this.

    Yes, there may be real effects we can't figure out right now, but I don't know that these distortions are any worse than what is already acceptable today.

    Of course the car doesn't have some weird fixed refresh rate to deal with either...

    The eyestrain study is a good idea.

    AS
    AS
  • So, what's next? Ultrasonic bathtubs? :-)
  • If you had a recording of what sounds were being played on the windows, you could use it to filter the sounds picked up by the laser mike. The spooks would have to trust you (the proprietor) not to provide foreign inteligence agencies with those recordings.

    Of course, you wouldn't do anything like play back a recording on the windows, would you? You'd generate white noise using a random number generator that was regularly re-seeded by way radioactive decay. Still, you'd have to get the spooks to trust that you were doing that, and to not record the noises played on the window. Perhaps you could cover the windows with plywood; that would also defeat a laser mike.
  • Oh, I'm looking forward to this. Bad enough people are putting speakers in their trunks so I have to listen to their music even when they can't. Now they can make their windshields blare the music. I worked in a video store some years back and it wasn't uncommon for people to park and crank up their stereos so we could hear them while they looked for movies.

    But on the bright side, I can take out their speakers with a rock while walking by. This may be a good devlopment after all.

    -

  • Say, you know what someone should do? Get some of this glass and use it as the windows for their restaurant or café. Then mention that fact to members of the intelligence community.

    They'll all want to eat and meet there. It would make using a laser mike impossible. :-)

    Around Washington, DC or some other city with a lot of spook activity, such a thing might fly, financially.

  • Umm...
    Wouldn't the glass be at risk of shattering at certain frequencies? (eek.)
    I think, if this technology is real, that it could be used quite effectively for noise-cancellation. Interesting idea. If the sound is really any good, it could be used to lower manufacturing costs quite a bit; Many speakers already sound better than I can hear, I just can't justify paying the prices asked for them.
    But if you could retrofit a house or apartment in a noisy area with windows that would reduce invasive noise levels, I'll go buy a cheap house out near the airport...
  • For the screen to work as a lens the thickness of the material would have to change over the curvature. The speaker would not cause that affect. Also, consider the rigidity of glass, any rippling would have to be very minute, more minute than the human eye could detect. Maybe I'm wrong.
  • There is a more technical discussion off of the company's home page:
    http://www.nxt.co.uk/
  • Hmmmm, what if I added a display to em....

    Instant multimedia.

    The DVD would be a bit uncomfortable
  • Or use 2 pieces of glass that were different densities. There would still be some phase cancelation, but as the denser glass would need less movement to reverse the image phase change, the sound wouldn't be completely cancelled. Also a vacuum could be placed between the 2 pieces of glass, limiting phase cancelation even more.

    Jon
  • I remember seeing this a long time ago - maybe in radio shack. Mount a transducer behind a wall panel, and essentially the whole wall becomes a speaker. I doubt if hi fi claims were made, but probably not terrible sound, depending on the wall panel and the room.
  • Normal glass isn't perfectly smooth just by itself. But if it makes you feel better, it would like have the same effect as smashing into a pane of glass with a piece of paper on it. Paper is pretty rough when you look real close. If you're still afraid - take a piece of paper and mash it on your face, just to be sure.
  • I bought a pair of Martin Logan's in October. I'd never go back to anything else. Cone speakers in boxes sound muddy as crap comparatively. Electrostats all the way! Sounds like these speakers work on a slightly different technology though, as electrostats need a large panel to vibrate at low frequencies. We'll just wait and see, I suppose.

  • I've got a pair of electrostats and I've never seen them vibrate, even with 250 watts running through them.

  • This was done already...there was a company (forget the name) that used to sell little
    transducers that attatched to glass/plexi/etc
    and made sound. It was tried in audio for stores,
    as in the glass windows would be speakers...

    Sounded really, really bad.

    number9

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