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Focusing Audio

Posted by CmdrTaco on Sun Aug 27, 2000 01:23 PM
from the screw-surround-sound dept.
Media Music
Alien54 writes: "The fine folks at the MIT Sound Media Lab have come up with a cheap and practical way to focus sound: "A beam of light can be controlled in many ways - it can be aimed at one person in a crowd, spread to fill a room, or projected to create rich, distant imagery. We can now do these very same things with sound. The Audio Spotlight can be used in two major ways: As directed audio, sound is directed at a specific listener or area, to provide a private or area specific listening space. As projected audio, sound is projected against a distant object, creating an audio image. This audio image is literally a projected loudspeaker - sound appears to come directly from the projection, just like light." While still under development, they are testing applications of the device in collaboration with several of their media lab sponsors in preparation for eventual commercial release."
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  • Poor frequency response? (Score:3)

    by nhm (39489) on Sunday August 27 2000, @08:58AM (#824334) Homepage
    All very interesting, but the information seems to suggest a bottom-end frequency response of a few hunred Hz. The figures, at least, seem to stop at 400Hz.

    Now... 400Hz is quite high really. For the musically inclined, concert A is 440Hz. Off the top of my head that's significantly higher than the fundamental frequencies involved in, say, male speech. Until they can get that extended down to somewhere closer to 150Hz (remember - this is logarithmic so one octave is a doubling / halving of frequency) I would think there will be difficulties in using it.

    Nick.

    PS - Did anyone count the number of `TM's around the place!!
  • SpotSpeaker?? Or AudioSpot???

    Maybe I should register audiospot.com now.
  • Dude, you sound like your stoned or something.
  • Invasion of privacy? Get real, you are in a public place that is owned by another person/business, you have no privacy.

    If they want to film you shopping to help them with product placements to maximise sales and profits, that is their right to do so.

    Grow your own food in your backyard if you want privacy about what food you eat.
  • >first, the stockholders of supermarkets aren't >necessarily "bourgeoisie". You can be A >stockholder, too; just buy some stock. And it's >possible for a supermarket chain to be entirely >owned by individual small investors like you. >And the chain would still practice sleazy >marketing practices; so, I don't see how there >is a class war at work here.

    Okay, we're really going off topic here, but c'est la vie :)

    Well, IANAM (I-am-not-a-marxist), but from what I know from studying their thought some, they would explain this as a cornerstone of the 'class war', since the reason that individual small investors buy stock, is so that they can get a monetary return on their investment, so that they can be richer; eventually joining the 'Bourgeoisie' if they are fortunate and or shrewd.

  • You've obviously never been to goatsex.

    (also, most amusement parks have stagnanted (ooh, a ride!); see the begining of 'house on haunted hill' for some of the new shit they're doing)

  • Never heard about the clockwise thing, and now that I think about it the larger supermarkets I frequent have entries in the left side of the store, so you move clockwise. The produce is near the entrance, and the frozen food is on the far right end. The "impulse" buys are near the counter of course, but now that I think even further about it I almost never buy anything from them. I wouldn't read too much into marketing research; they come up with some pretty wacky stuff.

    And slashdot has reduced me to writing about where the produce in my local supermarket is. Please, someone moderate me down as off-topic. I need it.
    --
  • The precision we could have surround sound with this?

    Six speakers? Phhhhpt! I have a sound laser creating speakers wherever they're needed out of my specially treated walls!

    Perhaps A wall with tiles that can vibrate/move independently from one another?

    Gfunk
  • That's incredibly unlikely. Firstly you have to have almost no will whatsoever to actually have this affect you in any way. Also you have to understand that even for the human subconciousness connect to the waking mind requires a great deal of personal training and the like (I've looked into it).
    The internet has breed a great deal of loonies who have found a bunch of other loonies who have absolutely no education in matters of science and the like and who don't have a very firm grasp on the validity of various theories. Logic contradicts a system that cannot be proven and there are a great many assumptions that are in this. Firstly the sound wave would have to be in a subvocal level which prevents you from actually perceiving it. Secondly when it's down that low you have to rely on a really sucker like Homer Jay Simpson to actually fall for it. Remember the studies back a number of years ago about putting subliminal messaging into advertising in the movies? Ever wonder why it dosn't seem to work absolutely (last time I checked I went to a movie there was a very obvious and very non-subliminal series of messages that I *could* see that were offering various drinks/candy/popcorn that blows that little idea out of the water really quick).
    Many people like to think that you can simply train people like Pavlov's dog and you just cannot. Human will would have to be about as low as a mental patient locked up for 20 years to get this to work.
    Even then it would only manifest itself as a possible desire and not as something that could easily be grasped in any traditional command and control sense. You would weed it out and then use your higher sense of logic to get what you needed. The American consumer is one of the most informed in the world when it comes to getting the most for the buck. Magazines like Consumer Reports and the like insure this.
  • According to the description of the device they use ultrasound in the millimeter wavelengths, this is in the hundreds of kilohertz. So your dog will not go insane, fido can't hear over 35kHz. These high frequencies are also attenuated rather rapidly in air.

    The coupling of these frequencies from the air to your body is also extremely poor. Compare this to a medical ultrasound that uses very high levels and is in direct contact with your body with gel to improve the impedance match.

    This definitely requires further study, but I wouldn't be too concerned about safety.

    ----
  • Audio Image (TM). That's nothing. If MIT had their way, they'd also own Computer Science (TM) and Linguistics (TM). It must drive the Media Lab (TM) nuts that they didn't invent the world wide web.
  • The idea was to create a "fart thrower," a flashlight sized audio device that could throw pre-sampled and newly sampled sounds across a classroom. <br><br>
    I followed up with Media Lab about this possibility and at the time (summer 1999) they were predicting two more years of development before it was commercially viable. Mattel wanted a toy for Christmas, so no go. Oh well- short sighted (sounded?) American business strikes again.
  • Uhm, wasn't there a Crackmonkey list thread about this? Something about 7hz? The C source that was posted contained this comment: /* Emits a 7-Hz tone for 10 seconds. True story: 7 Hz is the resonant frequency of a chicken's skull cavity. This was determined empirically in Australia, where a new factory generating 7-Hz tones was located too close to a chicken ranch: When the factory started up, all the chickens died. Your PC may not be able to emit a 7-Hz tone. */

  • Sonic guns (Score:4)

    by slickwillie (34689) on Sunday August 27 2000, @09:11AM (#824355)
    I'd like to have one mounted on my car. Then, when one of those "boom-box cars" rolls up next to me, I'll point my sound cannon at the driver and burst his eardrums.

  • Re:safety? (Score:3)

    by Chris Johnson (580) on Sunday August 27 2000, @11:51AM (#824363) Homepage
    It's quite possible that the device's direct beam could induce extremely severe headaches, either slowly or even right away. Supersonic frequencies are picked up by humans through bone conduction and not really sensed as sound per se, but they do play a role- when I want my stereo to convincingly reproduce the tonalities of incredibly loud sounds, I develop the high-frequency capabilities until it's able to produce very strong ultrasonic output, across the whole signal chain. This is known to be fatiguing to the listener- you have to rein it in quite a bit to allow continuous listening, because some sounds (for instance, abrasive raw electric guitars through peavey amps) are intensely fatiguing to the ear themselves.

    Do these MIT speakers kill bugs? Do they cause dogs to howl and cats to hide under the couch? The parallel to a spotlight is apt- it's not safe to look directly into a spotlight.

    1. The sound level is 80-90dbA. This isn't very loud: about the level of normal conversation at best. You throw that at a wall, and let it disperse, and you now have a whisper. They'll have to make it a lot louder, and that will be difficult because...
    2. The sound is created by generating a LOT of ultrasound, then letting it create mixing products in the audible range. Let me explain:

      Given two signals at frequencies f1 and f2 impinging upon a non-linear transmission element, the resultant signal will be composed of four frequency elements: the original f1 and f2, and two new elements (f1-f2) and (f1+f2). The power in the original signal will be split between the signals. The amount of the split depends upon the magnitude of the non-linearity: a completely non-linear transfer element will completely remove the origional elements, while medium that is only slightly non-linear will transfer only a little power.

      Now, the problem is this: air isn't very non-linear. So, to get a watt of audible sound, they are going to have to push, ohh, say 10 watts of ultrasound out of the speakers. One watt goes into sound, nine goes into heating of the air as it absorbs the ultrasound. Just what I want at the next (already smoky and hot) concert I go to: a megawatt of heat being added to the air!
    3. Given the general level of paranoia around here, I'm suprised nobody picked up on the fact that the same phased-array techniques that allow this to work can be used to make a highly directional MICROPHONE. Imagine one of these set up in a public place, suitably camoflaged behind ceiling tiles.
      Hey Joe, let's punch up what those two are saying: they look like dissidents

    Hmmm....
  • Marketing will have a field day with this. In grocery stores, each aisle will have secret messages aimed at areas to suggest you buy certain products (maybe even aimed lower, for the kiddies).

    How long will it be before satellites can beam down messages to whole geographic areas?
  • This is not new at all. American Technology Corporation [atcsd.com] already has such a system called Hyper Sonic Sound (HSS) [atcsd.com]. Their site also shows that they have filed for patents [atcsd.com] as early as July 1996 (first patent allowed August 1998 [atcsd.com]). I hate to break everyone's excitement, but the other thing about this company is that they don't manufacture anything themselves: they only license the OEMs (at least for HSS). It is interesting to note that one of their current contracts is to implement and test HSS technology for use on Navy Ships [atcsd.com]. I first heard of this technology about 5 years ago, to be honest, I don't know why more hasn't been seen of it.
  • Not so sure I believe in them, but that's another matter, I suppose

    It does work but I don't know what they're talking about when they say "nodal points."

    Here's how it's actually supposed to work: you wear headphones with a realtime DSP built in; the DSP tracks what is going on around you and calculates a sound that is 180 degrees out-of-phase with it.

    A very simple example: if you had a sine wave being produced in the room, it would generate another sine wave that is at an amplitude of -1 when the external sine wave is at an amplitude of +1. These two amplitudes cancel each other out, and you get an amplitude of 0.

  • I think that young children are probably very susceptible to this sort of thing. Children are unbelievably malleable.

    Furthermore, there are situations (most notably, the Nazi regime) where millions of educated and intelligent people became entranced by the illogical ravings of one man. There is plenty of anecdotal evidence that thoroughly intelligent people were completely oblivious to the truth (even though it was quite obvious).

    Of course, I don't think advertisers are quite this skilled; but still, things like this can happen.

  • Actually, we really made our mistake in 1944 (I believe I have that date correct). Ho came to the US and asked for help in negotiating a peaceful settlement with France. The US government pledged their help. However, for some reason (I don't remember what it was), the US Army *liberated* French POWs and gave their weapons back to them. As far as Ho was concerned, he had been betrayed by the US and by democracy in general. *This* is what really turned him against us. If it hadn't been for this, things might have gone much better.
  • Yes, but one of the stated goals is for people in cars to be able to listen to music independently.

    Additionally, where do you get the idea that removing 250-400 Hz band wouldn't be noticible? The lowest note on a piano has a fundamental frequency of ~27 Hz!

  • The universe is a big place. I guarantee you that there is much left to discover, even with mere thought experiment. For example, there is still a great deal to be done with understanding the application of basic anatomy to playing musical instruments. Dorothy Taubman has done much of this for piano while Claude Gordon has done it for trumpet. What about Violin? Harp? Theremin?

    Then, there are basic questions of philosophy. This realm of discovery is almost all thought experiment, and can actually lead to new discovery in the physical realm.

    Furthermore, never discount the ability of "untrained" laymen to learn and comprehend.

  • And I also wonder how on earth they can use this with John Coltrane if the lowest frequencies are "in the hundreds of Hz". Seems kind of useless for music to me.
  • It would not go unnoticed that there were large soundwaves at work. As soon as they hit their target (bowels, ears, etc.) they will bounce off and be audible elsewhere.

    -----------

    "You can't shake the Devil's hand and say you're only kidding."

  • NO.. he did no such thing.

    As for all the great thigns tesla did..
    he DID do great things.
    But people all too often confuse what he did with what he was trying to do.

    Tesla was a tinker, a hacker. Read his biography, it's great. He gets overlooked in the education system largely, and ignored at the smithsonian.
    Marconi's patents were revoked and attributed to tesla.

    He did not focus sound, though, at all. NObody has ever done this before.

    He did run low frequency sound through a pole sunk into the ground, and made nearby buildings shake by hitting their resonant frequency.. but this is exactly the opposite of 'focusing'.

    Sonic drills.. that's starting to happen already. Also.. I believe a year or so ago someone figured out how to create a standing sonic wave in a chamber (has to do with chamnber shape). This is really cool.. could be the workings of a motionless pump or something (standing shockwave.. layer of compressed air that can be 'moved and rotated' by computer.
  • Could someone please help me buy one of these for the guy in the cube next to me!?!?!?!
    If I have to hear Limp Biscuit one more time . . ..
  • Directional sound doesn't really help much there. Let's say the sound is directed straight at the driver's head. What energy isn't absorbed by his eardrums will continue on in the same direction and eventually outside of the car. What you would really want is better sound insulation (luxury cars are getting pretty good about this).

    Mind you this still could have its uses. With a little bit of effort, you could get the same loudness from a 50W source as, say, a 150W source, since you don't have all that omnidirectional sound energy. Just imagine if you could do the same for the sun :D

  • that used to be in the helpfile for borland C++ v2

    /*
    *Not a Sermon, Just a Thought
    */
  • ... Sennheiser Electronic demo'ed a prototype of a speaker with the very same technology earlier this year at the annual meeting of the german Acoustical Society (Dega). So this is not really groundbreaking news...

    It's strange actually to see someone move the 'speaker' and you can hear the sound source moving through the room...

    If you look very closely, you can see the speaker here:

    http://dega.itap.de/netz/d00_45.htm

    It's only a view from the side, though (N.B. the speaker is the flat silver thing that doesn't look like a speaker ;) )

    just my 2 ningis

  • Re:drugs vs. technology (Score:5)

    by Electric Angst (138229) on Sunday August 27 2000, @09:40AM (#824409)
    were drugs introduced into our society in order to prepare us for the emergence of technologies that would simulate heir same effect?

    Yes exactly. As a matter of fact, I am the intelligence behind such an operation. I personally manipulated the DNA of the first hemp plants to ensure that they would produce THC. The actual process of fermentation, that was me too. It really just involved fucking with some yeast. Of course, then I introduced it to man, in the forms of mead and wine, long before recorded history. I also did LSD (at least, I did the real work behind it. In fact, you name it, I put it here, so your feeble little minds wouldn't explode when you saw a laser light show.

    Believe me, before I altered space-time, the Disney light parade was an absolute killer.

    (Yes, of course this post is sarcastic. My user number is far too high to have been able to do that stuff...)
    --
  • Well,

    IIRC /. is also repeating itself. Again. Tho the inability to search old articles (hey, Rob! fix this) makes it hard to verify.

    But I definitely do recall a story about a big multi-speaker array; record localised sound using an array of mikes, and then play it back on the array to recreate the sound coming from the old location.

    Now all we need to do is figure out the phase interactions and you can make the array move the location anywhere you'd like.

  • Noise-cancelling use? (Score:4)

    by EricEldred (175470) on Sunday August 27 2000, @12:40PM (#824414) Homepage

    Can this technology be used to cancel noises as well as generate sound?

    I am thinking that current noise-cancelling technology seems to rely on headphones, since noise is generally omnidirectional. But if this technology were used to determine the direction of the noise source, and shift phase of sounds so the sounds appeared to be coming from the same direction, then one might not have to use headphones.

    For example, in a cubicle there are noises all around, from telephones to people talking, and it would be extremely useful to be able to selectively tune out the noises and work without headphones. Currently, I believe "noise cancelling" area systems just generate white noise, which doesn't fix the problem, only create more.

    The lower bass tones could be handled in an area system, I think, because they wouldn't be so directional.

    I mean, doesn't the world suffer from increasing amounts of "noise pollution" as machines proliferate in our increasingly urban environments? Many people including myself would love to be able to take action to control this environment for ourselves and filter out the annoying noises. A much better use than increasily annoying sales pitches beamed directionally at us without any choice.

  • You know, there's a difference between a socialist government and a communist economy.

    Canada and France are two examples of countries that have had socialist governments on and off for years. But these are not Communist countries. There's a big difference.

    And how about Cuba - sure, not much for freedom...

    Please re-read that sentence. Then read it again. Repeat as necessary until what you just said sinks in.

    --

  • I think a much better way of doing that will be once we have mastered cybernetics, neurology, whatever, and can simply wire our brains to eliminate specific sounds just by thinking about it. Okay, sure, it's a ways off, but still...
  • i can picture that now, mom walking through the grocery store with junior and they stop in the cereal isle. "psst, hey Kid! You love me right?", says a loveably cartoon character to the kid, "then why dont you ask mommy really nicely to buy me?". Of course the parents cant hear this conversation because its aimed at around their knees... Suddenly the little kid needs the box of cereal because he doesn't want mr.[insert cereal mascot here] not to like him anymore. you did that, you'd probably make a fortune... until people found out that is...
  • If I'm understanding it right, this could be pretty good for cubicles, eh? I'm thinking that I could have a full sound experience, while not disturbing my coworkers in the adjacent cubes -- cool!

    Alex Bischoff
    Interested in building a roof over your cubicle? [slashdot.org]
    ---

  • ... it'd be a boon for the hearing impaired in public spaces. Amplified sound targeted to where they are sitting/standing.

    I wonder if it could also be used as a weapon. Stun people with an amplified blast long enough to subdue them.

  • Wow, just think of the ventriloquist act I could have with this technology... Look out Howdy Doody, here I come!
  • Can you name a country that has/had a communist economy and a democratic sytem of gevernment? Likely not.

    The fact that you don't perceive this to reflect something fundamentally wrong with Communism is just a little amusing to me.

    Doesn't this tell you something? That maybe people, given the choice, would really rather do without Communism?

    Trying to use Vietnam as an example of Communism that "would've worked" is ridiculous. Vietnam was the Cold War writ small, not some Communist Eden.

    --

  • I love that phrase "Class War".

    What a perfect way to conjure up feelings of fear and hatred while issuing a call to arms for anyone that's ever felt knocked down a notch in our society.

    It's such a clever use of words, but it belies the duplicitousness of the people who use it.

    By conjouring up the image of an invisible barrier that keeps individuals from accomplishing their goals, you provide them with a convenient scapegoat on which to relieve all their frustrations. Hence the use of that dirty word "class". You have no control over what "class" you belong to, because it is forged into your being the day you are born by the evil powers that be. It also quietly discredits the notion that you have control over your own life and determine your own destiny.

    Then there's the use of "War". Wow. There is no more powerful imagery than that of horrific destruction and the senseless slaughter of precious human lives. And by portraying entrepeneurs as cold-hearted, armageddon-bent demon-spawn, you make it that much easier for your flock to forget that their "oppressors" are human too and that they too suffer and die.

    It might not even be such a bad lie, if this rallying cry for the envious wasn't such a dead end. By repeating it, over and over, you start to believe that it really exists and then you are trapped. Trapped believing that there really IS nothing you can do to help yourself. That everywhere you turn, there is some invisible force, plotting to keep you down.

    The reality is, nobody cares about you. Nobody is willing to expend the significant effort to defeat you at every turn because you simply aren't worth the trouble. The only person that really has any vested interest in keeping you down is you, yourself.

    --

  • Groupies (Score:4)

    by TheNightOwl (206911) on Sunday August 27 2000, @08:42AM (#824474)

    Hey you over there. Yeah you with the red dress. Come on up front. The bass player wants to meet you.

  • safety? (Score:3)

    by Anonymous Coward on Sunday August 27 2000, @08:44AM (#824477)
    It's nice engineering. But as the page itself points out, there has been lots of prior work in this area.

    One very important question is the safety of this kind of approach. The nonlinear effects can't be very efficient, and there must be a lot more energy in the ultrasound than in the audible sound. How safe is it to have large amounts of ultrasound energy beamed at you for extended periods of time? I think I'll stick with headphones.

    As an aside, the trademarking is taking on ridiculous proportions: "Audio Image (TM)"? "Directed Audio (TM)"?

  • Re:Random Street Corner (Score:3)

    by Derwen (219179) on Sunday August 27 2000, @08:45AM (#824478) Homepage
    Forget about ad potential, can you imagine standing at a street corner and hearing, "THIS IS THE VOICE OF GOD!

    Actually the article [mit.edu] states that " frequency response, depending on size, extends down to a few hundred Hertz."
    I think people will be more surprised than alarmed to discover that the 'voice of god' is a soprano .
    - Derwen

  • I think people will be more surprised than alarmed to discover that the 'voice of god' is a soprano .

    You mean it isn't?

    Ever see Dogma?

  • I think you're being a bit melodramatic, also :).

    First, the stockholders of supermarkets aren't necessarily "bourgeoisie". You can be a stockholder, too; just buy some stock. And it's possible for a supermarket chain to be entirely owned by individual small investors like you. And the chain would still practice sleazy marketing practices; so, I don't see how there is a class war at work here.

    Also, I would argue that the supermarket chains do indeed exist to provide a service to consumers. Although what the chains want is, as you say, to provide profit for their shareholders, the reason they exist is for the consumers. If they didn't, they wouldn't be allowed to exist in their current form. For example, it appears that Microsoft is currently doing a disservice to consumers, so the US government is considering splitting them up. If the supermarket chains also harmed consumers, the same thing would happen to them.

    Finally, you make it sound like there is a choice between "shop at exploitative evil supermarkets" or "starve". But there are lots of other options. You can get your food from smaller businesses you consider non-exploitative, or, if you really want to, grow the food yourself. These options are perfectly reasonable; if most consumers did not like being "exploited" by the big chains, they would all switch to smaller stores. This isn't happening; so, apparently most people do indeed find the big chains useful and choose to shop there because they feel it's to their best advantage. I don't see any exploitation here.

  • just think of the test cheating potential... why wasn't this around when I was in high school?

  • drugs vs. technology (Score:4)

    by friscolr (124774) on Sunday August 27 2000, @08:52AM (#824501) Homepage
    consider some of the most common side-effects of popular illegal (in U.S.A. and most) drugs - they alter our perceptions, causing us to see things that aren't there, or hear things that aren't there - "the tree man, it's talking to me"

    now a lot of these effects are being duplicated with technology, only they aren't altering the way our brain senses, they are actually creating pseudo-realities for us to exist in (was that ad on the soccer field really there, or was it digitally placed? did the guy sitting next to me see/hear the same ad?)

    were drugs introduced into our society in order to prepare us for the emergence of technologies that would simulate heir same effect? imagine what the world would be like if we were suddenly introduced to a whole bunch of mind-bending technologies. Drugs (and the knowledge of the causes of such drugs, for those who don't partake) gives us the background to understand these technologies.

    just a thought


    -f

  • Just put in a tracking device, several of these spotlights, and a network of audio pickups and you can have your phone calls directed to you with no headset.

    Now how to tell apart the people talking to nothing and the people on the phone...
  • I wonder if it could also be used as a weapon. Stun people with an amplified blast long enough to subdue them.

    IIRC audio weapons have been made with very low freq. audio meant to hit a resonances in people's abdominal cavities. The trouble with the low-freq audio was that it tended to be omni-directional, so it was difficult to aim the cramp-inducing sound field at, say, a crowd of WTO protesters without harming the good people manning the device. One could imagine, however, using multiple, highly columnated, directional beams of slightly differing frequencies (with a low-frequency beat wave) to zap individuals. The resonance is moderately narrow (again, IIRC--someone more in the know please correct me if I'm wrong on this), so the carrier may not need to be of exceptionally high volume in order to drive the resonance to useful amplitudes.

    It's been a long time since I read about these, but if I recall correctly the concept was inspired in part by a chicken farm located near a factory in Australia (perhaps New Zealand). The factory put out steady, low-frequency oscillations at a particular frequency that caused the chickens, when they grew to where their heads were a certain size, to die from having their brains scrambled.

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