A case for sending data over sound

An almost 100-year-old technology is seeing a resurgence.

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Tones have been used to communicate data for eons. Rudolph Hell's Hellschrieber machine, invented in 1929, could send audio tone pulses over any radio. If a tone was 'on,' the fax-like machine would create a black pixel, and if it was 'off,' it would be a white one.

You could communicate around the world like that, and tools like it were the precursor to audible touch-tones that are used to transmit phone numbers over landlines, as well as the fax machine.

More recently, we've moved over to light, rather than audio, for data transmission. Copper and satellite came somewhere in the middle.

But the Hellschrieber idea lives on.


A startup called Chirp thinks that sound and data should be used again, this time to share things. This approach aims to take advantage of the millions of speaker- and microphone-equipped smartphones that people have with them almost constantly.

Those devices can become audio encoders and decoders. Encode a sequence of letters as audio, play the audio, and any device within range decodes it and displays the text.


A smartphone app makes it all happen. The company says its communication medium is easier to use than email.

"Unlike email, you don't need to type in anyone's address," Chirp says on its website. And neither recipient nor sender have to be connected on a social network.

"Anyone running the app," within earshot, "can 'hear' the data," the company says. Website URLs are a suitable message to send, Chirp says. The user receives the text, then clicks on the URL, and is presented with a webpage.

'Internet of Sound'

And it's probably in this commercial aspect that the "Internet of Sound," —as Patrick Bergel, one of the Chirp founders terms it—is most interesting.

Chirp has broadcast qualities. More than one person can receive a "chirp." That means that you can send the two-second message over a public address system, radio, or multimedia such as a YouTube video.

"There are more tiny, cheap speakers on the planet than there are people," Bergel writes in a TechCrunch article.

"Why not leverage this ubiquitous, commodity technology? We see a huge opportunity to connect a very large number of devices simply and intuitively," he writes.

Other players

Chirp isn't the only attempt to delve into this area. LISNR is another communication protocol sending data over audio.

It's using tones to create proximity-based beaconing and says it's used its technology to supply music fans with behind-the-scenes content at concerts. It has also provided at-the-shelf product information, presumably at retail.

Google Tone is another sharing-over-audio idea. "It's a Chrome extension that broadcasts the URL of the current tab to any machine within earshot that also has the extension installed," Google explains on its website.


Interestingly, audio for data is also showing a resurgence in another avant-garde technology. Radio has been used to send encrypted bitcoin payments audibly—cutting out the Internet at the last mile.

I've written about Bitcoin over compressed digital audio and video before in "How a TV network is being used to move financial transactions."

"If it carries sound, it can send data," Bergel says. But then, Rudolph Hell knew that back in 1929, as did Morse before him.

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