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Embedding Data Signals In White Noise 239

Anemophilous Coward writes "ZDNet has the following article which describes a company that 'has devised a method for sending wireless signals over ordinary audio speakers so that humans can't hear them. With this same technology, radio stations can unobtrusively transmit ads, Web site URLs, or information about music and artists to in-car cell phones.'" Here is some further reading about the company, Intrasonics.
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Embedding Data Signals In White Noise

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  • by Dutchmaan ( 442553 ) on Thursday November 07, 2002 @06:36PM (#4620679) Homepage
    We all know this is just a cover story for the REAL secret messages in the static!
    • A hot new startup in California has announced a technology for encoding color information in black-and-white television broadcasts. The extra signal is encoded such that black-and-white receivers don't notice it, using a proprietary technique referred to as a ``subcarrier''. Millions of Slashdot kiddies are smitten with awe.
      • Actually, RCA Color, that to which you are referring, took many years to develop, and was originally not chosen by the NTSC.

        Orginally, the NTSC chose CBS Color ( a mechanically-timed color wheel system ) because RCA's "no moving parts" system was late and looked terrible.

        But RCA had an established Black and White user base, and the CBS color sets were incompatible, so CBS color sets didn't sell. A few years later, NTSC formally retracted their endorsement of CBS Color and endorsed RCA color, which hasn't changed for 48 years.

        I only wonder if the same shiznit is going to happen to HDTV, we'll be stuck in 480i land forever! :)
    • The one thing I can't stand about cell phones is the paucity of advertisements. It's really difficult, I go into withdrawal sometimes while on the phone, because there are no ads telling me what to buy. It's almost like being in a forest or cave! Thank goodness they are finding new ways to infiltrate the mental environment.
      • From the article:

        With this same technology, radio stations can unobtrusively transmit ads, Web site URLs ... to in-car cell phones. ... which my in-car spam filter will ably weed out and dispose of.

        There must be a better way to get ads to people... like when people actually want to look for a new product (what a concept!). Most ads I skip right by because I'm trying to get something done when they show it to me. I'm in a mental train of thought (a "zone" if you will) and actually reading and comprehending the ad would take me off of what I'm concentrating on doing - like if someone were to tap on my shoulder. Advertisers need to think of better places and times to get their ads to me, or give me a place to go to look for them (hey how about a catalog, huh?).
    • We all know this is just a cover story for the REAL secret messages in the static!

      Come on' this is /.! It's ALL static. ;-)

    • If SETI can't see it, it's not there or we don't know how to listen. Either way, it's all your fault Dutchman.

      Imagine, the universe is filled with spam. Ahhhhh!

  • what kind of bandwidth would this get? (early cop-out post)
    • Re:bandwidth? (Score:3, Informative)

      by fritz_269 ( 623858 )
      It seems like they're using psychoacoustic masking -- which really isn't a bad idea, as it won't change the perceptual SNR (unlike the spread-spectrum white noise espoused here). Psychoacoustic masking carefully removes bits of audio information that we would be unlikely to hear anyway. Dolby Digital gets about a maximum compression about 16:1, which would do for cheap-o speakers, but it would probably be placed more around 5:1 so those with nice stereos wouldn't hear the difference. MP3 uses similar masking compression ideas, and a 128k mono bitstream gets a compression of about 5.5:1.

      Let's assume some rockin' speakers with a 22kHz rolloff, and a great FM reception with 96dB Signal-to-Noise (and a very quiet listening room). That's approximately 16 bits at 44kHz or 704Kb/s of information. That has to carry both the audio and the data signal. The data signal would have to be mono, since most toys & cell phones don't have two ears (err, microphones). Now, you have a 704Kb/s bandwidth in which you only need about 1/5 = 140Kb/sec for good audio, leaving you with a theoretical maximum of 563Kb/s left for data. Put in some forward error correction and packet and coding and other overhead and you'll probably get something more akin to 200Kb/s.

      But wait! Let's assume a car with some poor tweeters with a 15kHz rolloff, and poor FM reception with 65dB Signal-to-Noise with road noise added in. That's approximately 11 bits at 7.5kHz or 82Kb/s of total information. Ooops! You've exceeded your channel capacity by almost 2x, and you'll pretty much get a big fat zero data bits.

      So, the makers have make a tradeoff ->
      1) Low data rates: significantly less than ~200kB/sec to accomodate cheap stereos but retain audio quality.
      2) Poor audio quality: significantly less than ~140kB/sec to accomodate higher data rates or cheap stereos.
      3) Lose functionality on cheap stereos: but retain both good data rates and quality audio for those who can receive it.

      My guess is that they'll just go to something tiny like 500b/s, in order to reach the most market share. Even at that rate, a text ad would come through right quick.

      I can just see the next Furby craze, now they get instructions (programming??) from the TV!

      Anyone know the max bandwith and SNR of NTSC audio?
  • by GeneralEmergency ( 240687 ) on Thursday November 07, 2002 @06:38PM (#4620703) Journal
    ....more invisible voices urging me to do bad things.
  • I only hope Mozilla can make a popup blocker for my phone.

  • by pheph ( 234655 ) on Thursday November 07, 2002 @06:38PM (#4620705) Homepage
    Blow your mind []
  • by ekrout ( 139379 )
    [A company] has devised a method for sending wireless signals over ordinary audio speakers so that humans can't hear them.

    Yeah, but how much is dog insurance going for these days?
    • If you would read the article, it says it does not do that. It would instead put it in noises the ear filters out.
  • by KnowledgeFreak ( 528963 ) on Thursday November 07, 2002 @06:40PM (#4620729)
    And life for all dog's everywhere will never be the same.

    • Except for the fact that the article SPECIFICALLY states that it doesn't work on the same principle as dog whistles as the sound couldn't be transmitted through ordinary speakers.
    • from the article: Does the company's technology work on the dog whistle principle, using sound waves that are below the threshold of human hearing? No. If it did, you couldn't send the signals over standard audio speakers. Instead, the technology revolves around what's called psycho-acoustic masking. Humans tend to filter out what they don't want to hear, especially the pop, fizz and hum of white noise. Intrasonics essentially takes and digitizes recorded messages, and then masks them as nuisance noises. The signals are spread over the audible spectrum and then disguised into the soundtrack. During a crescendo, the signals can be louder than quiet moments and still remain undetectable. A processor, equipped with specialized software, in the receiving unit then reassembles the message and delivers it accordingly. Tests reveal that people don't hear the signals.
    • ...and every time some RiceBurner drives by, spot tries to lunge into traffic...

    • by Jerf ( 17166 ) on Thursday November 07, 2002 @07:06PM (#4621011) Journal
      Others have already observed that it's not a frequency thing, but let me expand on that.

      Frequencies are already optimized for human hearing, and it's not usually possible to send, say, a 40,000Hz signal on most anything you can think of, analog or digital. Standard phones have a bandwidth of something like 3 K Hz. CDs of course top out around 20,000Hz, give or take a bit. (It's not a perfect cutoff at 22050, it's a curve, so there isn't quite a point you can say is "the limit".) I don't know for certain but I'd bet FM can't transmit those frequencies and be compliant with FCC regulations. (Of course the tech could do it in theory, but the radio station may have to leave their allocated frequencies to do it; I don't know for certain.) AM could do it in theory but based on the low quality of the signal I hypothesize that something is preventing high frequencies from getting through.

      Finally, the coup de grace is that our speakers are optimized for human hearing, pretty much no matter what. Covering the bases from 20Hz - 20,000Hz is a hard enough problem without pushing the required range up another couple of octaves.

      In fact, what the company is proposing seems to be in some sense the inverse of MP3 coding. MP3 coding strips the signal of things that you can't hear through by analysing what is psychoacoustically masked [] in the original signal. The MP3 encoding process can then focus on just the parts of the signal you do hear, which is obviously going to require less space, except in some pathological cases where the whole sound is perceivable (like a pure sine wave tone).

      From what I understand of the marketing, the part of the signal that an MP3 encoder strips out is exactly where they would place their data. They can stick any data they want in there and we just plain won't hear it, but a computer+microphone doesn't have this problem.

      Interesting corrolary: The time frame this will work in is limited, as digital transmission usually uses compressed audio, and the act of compressing the audio will preferentially eliminate this data. (Or does digital radio transmit an uncompressed stream?) They'd better get marketing this now, so that there's an installed base and they can try to later create receivers that will re-add their signal on the receiving side. Of course, if all anybody is using this for is advertising, I can't imagine we're going to go out of our way to buy "Advertising Enabled!" digital radio receivers.
      • If the CD digitally stores 44,100 samples a second, why isn't 22,050 an absolute cutoff? I would imagine it would HAVE to be, since it's not physically possible to make the wave go up-down-up-down any faster than 1/2 the sampling rate.)
        • by Jerf ( 17166 ) on Thursday November 07, 2002 @09:57PM (#4622179) Journal
          22050 is an absolute upper cutoff in the encoding system, and in theory you could encode a 22,049 Hz signal into Red Book audio. I said it's not a perfect cutoff because it's impossible to build an audio filter to cut off precisely at 22050 Hz, which is beyond the scope of a Slashdot comment; please consult a signal processing resource on how signal filtering works.

          At the recorder, you must cutoff signals over 22050 or risk the horrible problem of aliasing (again, out of scope of a Slashdot post but pretty interesting). Since you can't have a perfect cutoff filter, you generally can't record 22049Hz signals except with extreme attenuation (in the specific case of 22049, it will well below the noise floor). Generally, when the CD players re-construct the sound, they will also do some filtering as a side-effect of how they do it. So you can't generally play back a 22049Hz signal either, even if you directly encode it onto a CD.

          So while you can encode it, you can't record it directly and you can't play it back, so in a very real practical sense, 22049Hz is not usable with CDs. And so on and so forth for the other frequencies between 20000 and 22050. It's a smooth curve (and not necessarily the same one for two pieces of equipment, though my impression is that they have standardized somewhat because it's cheaper that way), so in a real-world CD recording and playback application, in a very real way there's no particular cutoff frequency you can directly point at, even though there's one in theory.

          In general, it's a pretty pedantic point. ;-) I just like to be precise when possible, and prefer practical realities to theoretical ones, which is why I'm in Engineering college.

          This, by the way, is part of the reason that CD's sample at 44100, instead of 40000. 40000 would be somewhat more efficient with the storage medium, but you'd have problems with the fact that you have no room to filter out the higher frequencies without hitting "good" ones as well. There are other concerns too, that's not the whole story, but it is a very significant part of it. In fact that goes for this whole post; I'm skimming over a lot because this is only a Slashdot post. (Like "20-20,000 is only a convenient fiction", the exact way filters behave, etc.)
          • Actually, you could NOT encode a 22049 Hz signal on a CD, unless the signal lasts for more than 1 second.

            When you chop a signal (turn it on and off), you are modulating it. Turning a signal ON, waiting a second, and turning it OFF are equivilent to modulating the signal with a 1 second long square wave. In the frequency domain, that corrisponds to convolving the signal with a sine(f)/f function, which has infinite bandwidth (though only the first lobe of the signal has appreciable energy) - as a result the modulated signal has a wider bandwidth (for a 1 second on/off cycle, most of the energy will be within 1 Hz of the center of the signal). Since the signal will have a +/- 1 Hz bandwidth, it will extend across the Nyquist limit.

            Practically, even at 4X oversample, you will have problems reconstructing the signal. Consider a sine wave at 20kHz being sampled at 80 kHz. If you sample the signal at 0, 90, 180, and 270 degrees, will get a full amplitude sine wave after reconstruction. Sample it at 45, 135, 225, and 315 degrees, and you will get a square-ish looking signal at sqrt(2)/2 the amplitude.

            Sample a 19.995 kHz signal at 80 kHz, and you will get a pulsation of the signal, since the sampling phase will slowly drift.

            That's why oscilloscopes usually sample at 10x or more of what the scope's rated bandwidth is - a 100 MHz bw scope will usually sample at 1Gsample/sec.

            (Yes, there are ways a scope can have a 1GHz bandwidth and sample at 1Gsample/sec, but they use tricks that only work on a repetative signal - don't try to capture transients with it).
          • At the recorder, you must cutoff signals over 22050 or risk the horrible problem of aliasing (again, out of scope of a Slashdot post but pretty interesting). Since you can't have a perfect cutoff filter, you generally can't record 22049Hz signals except with extreme attenuation (in the specific case of 22049, it will well below the noise floor).

            IANA-electrical engineer, but I believe the way this problem has been addressed in instrumentation I have worked with is to oversample the signal (record at 200 KHz for instance) and then just filter out the undesired frequences digitally. I have worked with NMR equipment which used this approach so that you can acquire data at any desired sampling rate centered on any particular frequency without needing all kinds of fancy adjustable filters and oscillators.

            In NMRs you are usually interested in collecting a signal with about 10KHz of bandwidth at a frequency of 500MHz, but the required bandwidth and base frequency can change. Also, if your data is going to be in a 2KHz range, you don't want to record 10KHz of bandwidth as the recording times can be serveral seconds long, and you are often acquiring this data every couple of seconds over a few days - disk space usage is an issue, as is FFT processing time.

            The solution is to just have the hardware set to record at 500MHz with a REALLY large bandwidth, and the hardware tosses out unneeded data before it ever gets recorded to disk. That lets you move the acquisition frequency around at will, and adjust the bandwidth as well.

            Again, I wouldn't be surprised if there are others wiser than I on this topic - but I believe in a nutshell this is how you can get around filter problems when you record. Now, the playback circuitry in a $30 CD player is probably still going to be a bottleneck - the data has to get converted to analog somewhere..
          • I said it's not a perfect cutoff because it's impossible to build an audio filter to cut off precisely at 22050 Hz
            Oh, I know about that, I just didn't understand what you were trying to say the first time around. By "it's not a perfect cutoff" I thought you were trying to say, "it's possible that some signals might work above that frequency", which isn't true. 22050 Hz is an the upper bound for *everything*, but only certain waveforms (rectangular pulses) can acheive it. Most complex waveforms you get in music will cut off at much less than 22050 Hz. How much depends on how good the listener is. For example, you might only be able to approximate a sine wave as a triangle wave if your resolution is so low that all you get is samples that go: up, middle, down, middle, up, middle, down, and so on. Many listeners won't be able to hear well enough at 11025 Hz (which is what gives you four samples per wave period) to differentiate between a 11025 Hz sine wave and a 11025 Hz triangle wave. So, no there is no good point at which you can state that is the cutoff frequency, but you CAN be guaranteed that it is always less than or equal to 22050 Hz (which makes that figure still be a metacutoff of sorts - it's the cutoff for how big the cutoff can be.)
      • Just FYI: The audio bandwith of stereo FM radio is about 18kHz or less. The stereo pilot signal is at 19kHz, and the Left-Right signal is centered at 38kHz. So the radio receiver is going to need some pretty good filters to produce the full audio bandwidth, and eliminate the 19kHz pilot.

        AM radio stations are only 10kHz apart so you are limited to less then 5kHz of clear audio bandwidth.

        This web page [] has some good info. It shows only 15kHz of audio bandwidth for FM stereo which is probably typical, but that is not a limitation of the specification.
      • They just taking "known" white noise and adding the signal to be encoded to it. You end up with slightly different white noise. At the other end you subtract the "known" white noise, and voila! there is your un-encoded signal.

        The only trick is making an algorith for white-noise and some how syncing things up.

        I'm not sure how they plan on using this.

  • Hey! (Score:3, Funny)

    by gpinzone ( 531794 ) on Thursday November 07, 2002 @06:40PM (#4620739) Homepage Journal
    I want an in depth analysis of the Beatles' White Album immediately! Charles Manson was right!
  • Ads" Unobtrusive"? (Score:2, Interesting)

    by jhouserizer ( 616566 )
    "radio stations can unobtrusively transmit ads"

    Is this really possible? - I guess so, as long as they're only "tansmitted", and never converted into a form that can be picked up by my eyes, ears, skin, tongue, nose, ...

  • Interactive CDs? (Score:4, Interesting)

    by sirshannon ( 616247 ) on Thursday November 07, 2002 @06:42PM (#4620754) Homepage Journal
    who will be the first artist to embed lyrics, trivia, etc in their CDs?
  • Is there no escape? (Score:4, Interesting)

    by Malcolm MacArthur ( 66309 ) on Thursday November 07, 2002 @06:42PM (#4620755) Journal
    Isn't it sad that one of the first things they think of doing is using it to send adverts?

    Advertising everywhere... no escape. I remember reading a short sci-fi story about this many years ago. Unfortunately, it looks like somebody else read it as well...

  • Exciting! (Score:5, Funny)

    by joebagodonuts ( 561066 ) <> on Thursday November 07, 2002 @06:43PM (#4620759) Homepage Journal
    The pr0n industry should be all over this. You can watch a movie at home with a special "doll", responding to commands...

    Where can I buy stock?

  • by Student_Tech ( 66719 ) on Thursday November 07, 2002 @06:44PM (#4620767) Journal
    I wonder if this technology could be modified to watermark the source of the signal?
    But if they are saying that it is random pops and cracks how will converting it into MP3s affect it?
    I guess also, how would extra noise because one has a lousy stereo do to the signal?
    • by outlier ( 64928 ) on Thursday November 07, 2002 @06:55PM (#4620893)
      how will converting it into MP3s affect it?

      Depending on how this is implemented, lossy audo compression techniques used in MP3 or OGG may strip the info. One of the reasons that these formats can get such good compression rates is that they strip a lot of the acoustic information that people can't hear -- which is exactly where these guys are looking to put their signals.

      My guess is that someone could come up with a lower bandwidth approach that would remain in the signal after compression. But they'd probably have to tailor their approach to the specific algorithms in a particular MP3/OGG encoder. If someone used a different encoder or the encoder was upgraded, a new solution would need to be created.

      Of course if this technology is primarily used for advertising, then people would want to strip the information. If, on the other hand, the data were truly useful to users, there might be an effort to preserve it after compression.
      • Of course, if you're implementing a digital stream in the first place, it is MUCH better to just stuff the metadata into the stream as binary data as well. Which is what all the digital formast do. The domain for this solution is only full-bandwidth uncompressed signals, which are going to increasingly be a thing of the past.
      • I expect that newer encoders will show you what the embedded info is, and allow you to put it into the tags. Assuming this tech takes off.
      • This is really interesting from a watermarking perspective. Think of any Industrial song that makes use of sampled static. Just because it is noise, does not mean it gets filtered out by the codec. The noise is part of the signal.

        You may expect steganographic stuff to get munched, but what if the watermarking software identifies noisy passages and replaces them with apparently random "noise" that is your watermark? Unless you knew about it and delberately munged "noise", your codec would try its best to *preserve* that signal. Filter too much of the timbre (aka noisiness) out of your signal and it starts sounding lifeless.

      • The idea behind the lossy audio codecs such as mp3, ogg, etc, is, is to allow a quantization noise spectrum at exactly the (frequency-dependent) threshold of hearing, which changes depending on the active sounds.

        Any inaudible 'hidden' data will also have to be below that same threshold, otherwise it would be heard.

        Hence, if the audio codec doesn't remove the hidden message, then it's not optimal or you're encoding at a too high bitrate.

    • The thing about perceptual codecs is that they only try to preserve the information that is perceptible. Thus, any imperceptable information, like white noise or watermarking, will tend to get stripped out. And even if a system can carry through a particular compression technique, it might not work with other, future, more advanced techniques.

      This whole technology is based around sending full-bandwidth signals, which is definitely NOT the trend in digital communications.

      Stegography-like stuff requires lossless compression ala GIF. Doesn't work well with JPEG!
  • by burgburgburg ( 574866 ) <splisken06@ema i l .com> on Thursday November 07, 2002 @06:44PM (#4620771)
    This is just like that time that the phone police were sending me those messages through the rings, man. Exactly the same, except different. Man.
  • stations can unobtrusively transmit ads...

    How effective can an ad be if it's unobtrusive? And if an ad is ineffective, the who would pay for it?

    I suspect that this will become a method to obtrusively transmit advertisements.

  • This could be used to watermark audio, in order to try to track pirates. Granted, if they are actually using psychoacustics, then psychoacustic compression systems like MP3 or Vorbis would strip the extra data, but this would be good for basic audio.

    However, I doubt this is "inaudiable" - rather I suspect it is "unobtrusive" - you would hear it, and if you know what to listen for would identify it, but you wouldn't find it objectionable in most cases.

    But keep it the hell off my CDs!
  • Wireless phones don't just pick up random waves in the air, they pick up signal being sent to their phone number only. So how will this work?
  • So? (Score:4, Insightful)

    by shoemakc ( 448730 ) on Thursday November 07, 2002 @06:44PM (#4620787) Homepage

    Let me guess, by using the correlation of psuedo-random noise sequences summed with the signal. :::yawn:::

  • by moebius_4d ( 26199 ) on Thursday November 07, 2002 @06:45PM (#4620796) Journal
    This is an interesting idea, using psychoacoustic modeling to open a data channel in audio. The article describes some applications, and I'll certainly admit that some of them sound irritating or possibly dangerous (from a security standpoint.) Others sound better.

    But not everything interesting to do with this will be done by the company involved, because it may not make good business sense or they may not have thought of it. I'd be interested in what slashdotters can think of to do with such a channel. The obvious use of embedding artist and recording information is mentioned, and I like that one a lot. It would be great to have a radio displaying those things, and to be able to scroll back and look at the last N songs. This would let you find out what that song you heard the end of was, or do a statistical analysis of a station's playlist, whatever you want.

    A use that occurs to me is adding the information to advertisements so that adverisers can automate the task of making sure that they get what they pay for. Even performers could use an "ad id" check to make sure they get their voice-over royalties and the like.

    Of course, voice of america and similar programs could use this right away. First they start adding this hidden content to all programming, using encrypted books, articles, or any other easily accesible source. They can then easily put a specific message with a specific key into a program that certain people can unlock. There's no entropy difference between the "real" message and the usual dummy ones to detect.

    Hmmm lots of fun to be had here...
    • Note that it is not free data capacity for existing radio stations either.

      Filling up the frequency gaps with data up to the treshold of hearing (which would be utilizing psychoacoustic modeling to open a data channel) would increase the total power output of the FM transmitter for the same strength of the audible part. Hence, an FM transmitter of a particular maximum power output would have a smaller range when they start using this. Since increasing the transmission power of a radio station often is often not financially or legally an option, stations will only do this if this data more than compensates for the smaller coverage area.

      For embedding artist and recording information, there already has been RDS for almost a decade now, which has more than enough bandwidth for that.

  • by gr ( 4059 ) on Thursday November 07, 2002 @06:45PM (#4620797) Journal
    Using a seemingly innocuous message as a carrier wave for a truly useful message you don't want other people to know about is an old-news crypto technique, of course. But here's a fun, new place to apply it.

    And you don't even need to seem to be doing anything funny during decoding (the message would obviously have to be enciphered; pass it in the clear and anyone who owns a cell tower between the two points can read it); build that into the phone/PDA. With the ridiculous proliferation of the damn things, no one will blink if you receive a call, chat for a few minutes, and then tap a few buttons. For all they know, you're sending an SMS, even if you are entering your passphrase.

    All it really takes to do 3DES or Blowfish in software in a reasonable period of time is a StrongARM or similar (my Newton's got one, you cell phone must), though you'd get far better performance doing it in hardware. (Watch out for escrow, though!)
  • by M00NIE ( 605235 ) <poweredbystrutsg ... IONcom minus cat> on Thursday November 07, 2002 @06:46PM (#4620801)
    Or rather...

    Ignore the messages embedded in this whitenoise.

    You will Loooooooove Microsoft
    You will Haaaaaaaate Open Source
    Linux is eeeeeeeevil
    War on Iraq is goooooooood

  • Oh Great (Score:4, Interesting)

    by Gudlyf ( 544445 ) <gudlyf.realistek@com> on Thursday November 07, 2002 @06:46PM (#4620802) Homepage Journal
    Now we'll have to worry about some sicko blasting tunes as he drives by my house, sending the latest ad for "When Animals Attack 7" to my cellphone.

    Hm, could someone send a mass-broadcast virus this way?

  • by migurski ( 545146 ) <[mike] [at] []> on Thursday November 07, 2002 @06:46PM (#4620803) Homepage

    I find it sad that everytime a new technology such as this is developed, the first instinct of the marketing people tasked with selling it is to figure out a way to make it push ads into my perceptual environment, almost guaranteeing an initial cynical reaction..

  • Animal rights activists will surely love this "innovation" - even though the average human ear cannot hear these messages, it is very likely that we will see a large variety of animals go cracy if technology like the Intrasonics gets popular.

    ** And as it took 5 minutes to download PDF [] with only marketing jargon, analysis of an Slashdot Effect [].

    Really, somehow the Intrasonics thing sounds like even more outrageous marketing stunt than for example posting a link to a slashdot effect analysis. Or, if someone from the company is listening, please do provide some real technical specifications on the thing.

    • even though the average human ear cannot hear these messages, it is very likely that we will see a large variety of animals go cracy

      Well the article says that they spread the encoded data throughout the spectrum, not that they place it frequencies that we normally can't hear. My understanding of animal hearing is that they hear frequencies that we can't. Assuming that this is the case, then animals shouldn't be too affected, if at all. I'm definitely not a scientist so I may be off base here, but my first thought too was that they were using inaudible frequencies, but the article seems to suggest that they don't. Which would make sense since your average oem car speaker would have a pretty tough time reproducing sound at frequencies high enough.
    • oh, once again, feel free to moderate my previous post down. I missed the point, which is in this one chapter:

      Does the company's technology work on the dog whistle principle, using sound waves that are below the threshold of human hearing? No. If it did, you couldn't send the signals over standard audio speakers. Instead, the technology revolves around what's called psycho-acoustic masking.

      However, I would still like to have someone explain how this will work in reality. What kind of performance will be required to catch and decode these messages. It does not seem like a very light task.

  • by dameron ( 307970 ) on Thursday November 07, 2002 @06:49PM (#4620831)
    "I can hear it, can't you?"


  • Will my pet Hamster Fred, freak out ? Inaudable usually means higher sound frequencies. If it is audible but comes off as white noise ... I hate white noise. The humming of all this equipment drives me MAAAAAAAAAAAAAAAAAAAAAAAAAAD!!
  • Outside of Marketing meetings, I can't see how anyone would actually *want* their devices to respond to commands imbedded into audio noise. OK, a "Talking Tina" doll that acts the part during the airing of a Twilight Zone would be funny the first time around, but that's about all I can imagine the end-user wanting the technology to do (silly little tricks with "intercative" robots). I don't think that ANY consumer would want their cells to ring with the "ad of the day" transmitted over the air muzak at their favorite retailer.

    Wait, I just thought of a use... a prankster's dream come true. Imagine 40,000 cells all ringing at the same time during the playing of a *special* version of "Black in Black" during a major sports event. Or even playing a *special* CD in a boombox, laughing as everyone within listening range has their cell ring and deliver them a message that has been imbedded into the CD sound. Good luck tracing that obscene phone message.
  • Here is the "further reading" PDF [] from the linked site.

    Mirror provided by Mr HOSTBOT []

  • Can someone please tell me how to remove this pop-up ad that's sticking out of my ear? Everytime I think I've gotten rid of it it comes back.
  • by PineGreen ( 446635 ) on Thursday November 07, 2002 @06:57PM (#4620916) Homepage
    The Radio Data System [] has been around for ages and it allows precisely that: transmitting extra information with normal radio signals... Because it works by putting digital signal into inaudibile frequency, it should do exactly the same, as long as speakers have any response at 20-40Khz.
    • by Anonymous Coward
      >inaudibile frequency

      RDS signals are not only inaudible they are heavily filtered out before the audio stages of the receiver.

      A european FM radio carrier has mono audio
      at 0-15KHz, a pilot tone for the stereo decoder at
      19KHz, a stereo difference signal around 20-35KHz
      and RDS data above that.

  • question... (Score:3, Funny)

    by vmxeo ( 173325 ) on Thursday November 07, 2002 @06:58PM (#4620935) Homepage Journal
    "With this same technology, radio stations can unobtrusively transmit ads, Web site URLs, or information about music and artists..
    Humans tend to filter out what they don't want to hear, especially the pop, fizz and hum of white noise."

    So if I understand this correctly, the technology can transmit advertisements, spam, and pop music completely unheard by the human ear by disgusing them as advertisements, spam, and pop music?
  • A long time back, I was reading some hardware reviews on sound cards. 1 of the reviews mentioned a card that was rather nominal, but came with a special set of headphones. In about a page of article, it glanced over the soundcard and then went into rave reviews of the headphones, which apparently used "white noise" to block audible frequencies except for the music/etc coming through the headphones.

    My guess would be that this could be used to create a signal, and block it from human perception but perhaps still allow it to be picked up be electronics.

    One question I have though, if they're making such advanced uses of white-noise technology now, and these headphones/soundcards came out over a year ago, why haven't I seen rave reviews on the technology and white-noise headphones available at every radio shack? From what I remember, including the price of the card the 'phones weren't that expensive.
  • It'll get published by 2600 and then every kiddie will be encoding messages and sending them out through their little radio shack fm transmitters as mommy and daddy roll down the highway, making the technology useless (or even more useless)
  • ...sending wireless signals over ordinary audio speakers so that humans can't hear them....

    Is it just me, or does embedding data in white noise "sound" like it's already happend? Every time I pick up the phone when someone else is using the line for a dial-up connection, I am abruptly reminded of the transmission of data using seemingly random noise....

    $ # Patent pending...
    $ bzip2 -c </lib/ >/dev/audio

    And how is this diffrent from steganography + a pair of 2,400 buad modems?

    Besides, elephants [] have been doing this [] for millenia (with their feet instead of over their THX system).
  • Isnt this the story of the Movie The Ring?
  • by mbourgon ( 186257 ) on Thursday November 07, 2002 @07:17PM (#4621123) Homepage
    One of the things that came with the cuecat kit was a rca cable that was meant to go from your computer to your sound card. Apparently, while watching TV they'd embed a signal into the audio that the cuecat software would pick up, and it would take you to their site.

    Since one of our local channels was owned by the Belo corp (who owned a LOT of Digital Convergence stock), they pushed it HEAVILY, and embedded URLs in the news program.

    So, nothing new.
  • The company has discovered that by adding static and degrading your music quality they can send data over sound waves! Woohoo! You know, like a modem! Err, actually it's only half a modem, it's only one-way! I'm going to use another exclaimation point!

    After a pretty thorough search I was unable to find a data rate for this new top sekret modem technology. I'll confidently wager it's going to be between 10 and 100 baud, as in a 0.01K modem or 0.1K modem.

  • Wouldn't something like this easily fall into it? It'd be interesting to do a study to see if people responded to stuff transmitted just on the fringe of their hearing range.

    This kinda scares me a bit. I feel the sudden urge to rm -rf /; insert microsoft XP CD.
  • Compare it with RDS (Score:4, Informative)

    by Psychic Burrito ( 611532 ) on Thursday November 07, 2002 @07:48PM (#4621367)
    In europe, there exists a similar technology called RDS [] for "Radio Data System". It's on the air for about 10 years now and allows for these cool features since then:
    - Show the Station name in your radio display
    - Show what's playing
    - Certain stations are transmitted over several frequencies. RDS knows the alternative frequencies of your stations and automatically switches to the best frequency
  • Infrasonic (Score:2, Interesting)

    by jezreel ( 261337 )
    I remember a broadcast I watched on TV half a year ago. It was how to use infrasonic soundwaves to create atmosphere in cinemas. With all that THX and Dolby-stuff around two sound engineers who had worked together as close friends suddenly started to fight each other over something in the sound studio. Afterwards they realized that their mood had been seriously affected by unherable infrasonic soundwaves they used for the movie they were working on. The reporter said that this is used in pretty much every new movie to create an atmosphere of fear or rage among the viewers. I wonder how far this could be taken...
    There also seems to be a strange deep sound around in Europe. Nobody, not even the scientists measuring some American farts deep into the bavarian woods, was able to determine the source of that sound yet. Over 1000 people in Europe seem to be affected by that. They even made some conlusions about global soundwaves created by military sonar and stuff. Pretty scary...

    So I'd like to know about every stupid signal I will get, purely encoded data or else. I'm not a technophile but those stuff scares me because I won't be able to switch off the router or TV anymore...

  • Radio is limited to about 16 Khz on FM. Most of us can easily hear that. So they up the noise floor a little to make room for ads?

    Does this mean we get fewer audio ads in trade for the lower quality?

    Pipe your radio through lame, output through sound card, information gone all done!

  • Another method for the delivery of spam. Guess we'll have to start work on the anti-white (black) noise generator.

  • by TheSync ( 5291 ) on Thursday November 07, 2002 @08:47PM (#4621732) Journal
    Check out the Portable People Meter [] from Arbitron. It can recognize subaudible watermarks in music including over radio, Musak, and even some streaming audio compressions. Arbitron uses it for ratings purposes.

    Of course, then there is IBOC from Ibiquity [] which is an on-channel digital enhacement for AM and FM signals, part of which could be used for datacasting [], as part of most DTV signals will.
  • MP3 and OGG are essentially based on filtering OUT audio that would be not be heard due to psychoacoustic masking :) ..... so.....guess what? :)

    Just chain a realtime OGG encoder to the incoming music stream and it should strip the info! HEHE :) OSS to the rescue fighting unwanted ads again!
  • by Psx29 ( 538840 ) on Thursday November 07, 2002 @09:49PM (#4622119)
    This technology could encode bits in it that tell recording devices they can't record. I know what you're thinking: use old technology. But what if you record this and then all the new cd players detect this flag? Any other thoughts on this?
  • by randomErr ( 172078 ) <ervin,kosch&gmail,com> on Thursday November 07, 2002 @10:04PM (#4622228) Journal
    This is Push technology, so you could do any kind of push you do with channels now you can do with this. Here a couple of idea's I had:

    Song Titles - How about ID tags so you can actually see the exact title of the song your listening to? You can keep a 10 song list like caller ID. You can see the last few songs you listened to. For advertisers you would keep one text line scrolling on the display.

    Second Audio Channel - A secondary program at AM quality on an FM station. Kinda like how HDTV can have up to 6 lower quality channels.

    Radio for the Death - Close Captioning of radio lyrics. 'Nuff said.

    Emergency Broadcast Technolgy - Give both a readable text warning and GPS cordinates of pending danger.

    Exact Station Date and Time - Isn't that what you really want half the time you turn on the radio anyway.

    Weather and News Broadcasts - Get the local or national news in an instant.

    Automatic Request line # - Never have to listen for those damn # to call while your driving.

    Possible interactivity - Broadcast a survey to a cellphone, you log your answers, and then you transmit your results.
  • Embedding data signals in white noise is the easy part. It's getting them out that they haven't figured out yet.
  • Considering that a modem carrier sounds like noise anyway, it seems that this was only coming soon to a mall sound system near you. But does this mean that the bells I hear in Robinson's May while my wife is shopping will be carrying other data? =)
  • Song title/artist (Score:4, Interesting)

    by krnlpanic ( 221192 ) <krnl&krnlpanic,com> on Friday November 08, 2002 @10:26AM (#4624857) Homepage
    I have always liked when I put a CD into my player and the name of the song and the artist comes up on the LCD screen. Wouldn't the use of the "White noise effect" allow radio stations to transmit this information to radios for the same display purpose?

    *song is ending* "Damn, I love that song, I wish I could remember who sings it. Maybe the DJ will say the song title before the next song comes on." Oh wait, DJ's don't do that anymore...Just show it to me on the LCD!

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