Embedding Data Signals In White Noise

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.

Comments

OK....Where's my tinfoil hat?

[Dutchmaan]

We all know this is just a cover story for the REAL secret messages in the static!

Oh Great.....

[GeneralEmergency]

....more invisible voices urging me to do bad things.
.
.

For those who don't know what white noise is

[pheph]

Blow your mind

Why does spot keep beating his head on the ground?

[KnowledgeFreak]

And life for all dog's everywhere will never be the same.

Exciting!

[joebagodonuts]

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?

MP3s and Watermarking

[Student_Tech]

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?

Re:MP3s and Watermarking

[outlier]

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.

Applications vs intentions

[moebius_4d]

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...

I can hear the audiophiles now...

[dameron]

"I can hear it, can't you?"

-dameron

Not based on frequency

[Jerf]

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.

Re:Ignore the man behind the curtain

[Dannon]

"Can you hear me now? No? Good!"

The CueCat had this...

[mbourgon]

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.

Better use of technology

[randomErr]

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.