Hiding Data in Music Might be the Key to Ditching Coffee Shop WiFi Passwords

Hiding Data in Music Might be the Key to Ditching Coffee Shop WiFi Passwords

In a move guaranteed to send audiophiles recoiling back into their sonically pristine caves, two doctoral students at ETH Zurich have come up with an interesting way to embed information into music. What sounds crazy about this is that they’re hiding data firmly in the audible spectrum from 9.8 kHz to 10 kHz. The question is, does it actually sound crazy? Not to our ears, playback remains surprisingly ok.


You can listen to a clip with and without the data on ETH’s site and see for yourself. As a brief example, here’s twelve seconds of the audio presenting two versions of the same clip. The first riff has no data, and the second riff has the encoded data.


https://hackaday.com/wp-content/uploads/2019/07/ZTH-no-Filter.mp3

You can probably convince yourself that there’s a difference, but it’s negligible. Even if we use a janky bandpass filter over the 8 kHz -10 kHz range to make the differences stand out, it’s not easy to differentiate what you’re hearing:


https://hackaday.com/wp-content/uploads/2019/07/ZTH-with-8k-10k-filter.wav

After many years of performing live music and dabbling in the recording studio, I’d describe the data-encoded clip as having a tinny feedback or a weird reverb effect. However, you wouldn’t notice this in a track playing on the grocery store’s speaker.


Why Use Audible Frequencies?


Why in the world would you want to use an audible frequency to transmit information? The easy answer is that there are already audible transmitters and receivers everywh ..

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