Sound Code: Subliminal Data Transmission through Audio Waves

Have you heard of sound code? It may be the next big breakthrough in marketing and online commerce. It could also be an exotic technology only applicable to a few very specific set of industries.

What is it?

Sound waveSound code is a family of techniques to embed data into sound waves. It is a bit like ye olde 300 baud modem tied to acoustic couplers but with one important difference: the data embedded inside the audio signals shouldn’t be audible to humans. That is when people hears the sound, they shouldn’t notice that there are additional data piggybacked to it. Piggybacked you say? Yes. A carrier audio – which may be music or even simple speech – hosts the extra data and people should only be able to pick up the carrier audio and won’t recognize the presence of the sound code inside it. The technique is analogous to the way color printers insert tiny yellow dots in each printed page to identify the printer’s serial number.

No no, this is not about subliminal programming, so take your earplugs and tinfoil hat off. The idea is not to program human beings but to embed messages intended for processing by other electronic devices. Sure, similar techniques may be used to talk to the subconscious mind, but let’s save that for another discussion.

Because people aren’t suppose to notice the extra data in the carrier audio, there isn’t much bandwidth available for this additional baggage. Consequentially the amount of information that can be incorporated is small and thus tend to be tokens that points to the real data, like a URL or a unique number. In this sense, sound code is equivalent to QR code but for sound. If QR codes are small tokens of information embedded in pictures, sound codes are embedded in music or speech. One plus point is that sound code are concealed from the human ear unlike QR codes that are visible and often sticks out like a sore thumb.

Who are involved?

As of this writing there are two companies that provides the technologies for sound coding. Each has their own unique way of embedding information in audio data:

  • Intrasonics modifies the carrier audio and adds artificial echoes to it. The human brain perceives these as natural echoes and just ignores them as if there are a few insignificant objects that bounces the original sound.
  • Sonic Notify inserts ultra-high frequency sounds to the carrier audio. These frequencies are beyond the hearing range of most people and thus people just perceive it as if there were no alterations.

Both companies offers development kits and 3rd-party licensing of their algorithms. They also have free iOS apps that you can use to evaluate their algorithm’s performance for your intended use case: Euphonium (Intrasonics) and Sonic Experiences (Sonic Notify).

Each company also appears to carve different niches of the market. As of this writing Sonic Notify is more aligned towards musicians whereas Intrasonics tend to pursue big media companies and joining forces with Capablue that supplies set-top boxes for UKTV.  Lady Gaga used Sonic Notify to allow her fans to vote for the encore song during a performance. Whereas Canadian TV producer Cineflix deployed Intrasonics‘ technology to allow viewers play along real-time with the contestants in one of their reality TV show.

When this all started?

The idea and techniques for audio coding isn’t really new as there are a number of scientific journals written on the subject as far back as 1999 (Data Hiding Within Audio Signals, Petrović et. al.). However recent advancements in the processing power of mobile computers (think smartphones and tablets) have just made it practical.

Intrasonics also have a number of patent applications related to the technology and they prominently lists them in their websites. I’m not a patent lawyer, but hopefully the patent office doesn’t grant them a blanket patent that makes it easy for them to troll and stifle innovation (like the Lodsys in-app purchase or even the Windows 8 tiles’ lawsuit cases, to name a few). It’s quite clear from those journals that they aren’t the first to discover the idea, although their specific implementation could be novel and worth protecting.

Other Uses

What other areas can sound code be used? Here are a few from the top of my mind.

  • Exhibitions – museums, art galleries, and the like can provide links to additional content related to the exibits, embedded in each room’s elevator music. In these situations, QR codes placed near the exhibit’s label may be awkward to scan (at a semi-crowded room or perhaps covered by another person) and thus sound code can be a good alternative.
  • Radio shopping – sound code could be embedded into radio advertisements that contains links to the product’s purchase page. If the listener is interested, she could pull up the app, make a purchase immediately and then have the product delivered to her doorstep.
  • TV shopping – pretty similar to the radio shopping case and it’s primarily as a complement for QR codes when it can only be displayed as a small inset and may be difficult to scan.
  • Digital Rights Management (DRM) – sound code can be embedded in music or movie files and contain information the licensee’s information. This won’t prevent the media from being copied but if it’s copied to a public download site, it’ll be quite easy to identify the perpetrator. A similar technique is used by Safari Books Online on its downloaded content – the customer’s name and e-mail address are watermarked into each PDF file downloaded to discourage him from re-distributing the file.

What does this all mean?

Frankly I fill that the adoption of sound code will somewhat follow the growth curve of QR codes, at least as a consumer technology. Which is terribly slow. QR code was introduced in 1994, standardized in 2006, and by 2012 only 9% of US adults know what to do with it.

The biggest hurdle with sound code is – like QR code – end users need to download a special application to their smartphone to decipher these codes, an application that they likely won’t use for any other purpose. In other words, this requirement adds friction to its adoption and requires people to change their behavior – that needs to be externally motivated.

QR code was developed in the manufacturing industry where it was used as a lower-cost alternative to barcodes. It finds its niche there and also in the courier industry where it is used to tag and keep track of packages. In these situations, both the publisher of the code and the people who scans them are equally motivated and have similar goals: tracking boxes. When applied as a consumer technology, there isn’t much motivation for the consumer to scan these codes.

Thus sound code will likely thrive in similar niches as QR code – as a tagging mechanism where both the producer and consumer of the code shares a similar goal. Examples include indoor navigation of automatons in warehouses or office buildings and forensic tagging of copyrighted multimedia files. Lady Gaga may had some success to motivate her little monsters to pull up Sonic Notify’s app, but it’s a long, long, way from people attentively listening to radio advertisements with their sound code app primed and ready to buy stuff from the advertisements that the DJ plays.

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One thought on “Sound Code: Subliminal Data Transmission through Audio Waves

  1. Wow! It
    is really good for me to know that it is possible to send data through audio
    waves. Sending data over a long distance is not a problem now. We can
    transmit our data even audio data via optical networks.

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