Science & Technology

Scientists Found a Way to Transfer Data Through Music

Imagine a world where you don't have to ask for the Wi-Fi password in hotels or cafes. Instead, the access data is transferred through music — and no, it's not a jingle that spells out "P-A-S-S-W-O-R-D-1-2-3." A team of researchers at ETH Zurich recently developed a technology to store data using musical notes that are imperceptible to the human ear but can be easily interpreted by a smartphone.

A New Wave

Some common wireless communication technologies, like Bluetooth, use radio waves to transmit data between devices. However, Bluetooth requires users to pair devices in order to share files or photos — and as anyone who has struggled to find a friend on AirDrop knows, Bluetooth can be finicky.

This new technology uses a simpler medium: sound. Every cell phone is already equipped with a built-in microphone that can pick up audio data from a piece of music. Decoding the data could be as simple as downloading a smartphone app that contains the algorithm developed by the ETH Zurich team, although the app is not yet publicly available.

While companies like Chirp and LISNR have been experimenting with sound wave data transmission since 2009, what sets the Zurich team apart is their mission to integrate data into music without affecting listening pleasure.

The scientists used notes at very high frequencies — so high that the human ear barely registers them — to signal where the decoder algorithm should look for data. Then, over the dominant frequencies in the piece of music, they added slightly higher and lower notes at a quieter volume. These overlaid notes are what carry the data.

"When we hear a loud note, we don't notice quieter notes with a slightly higher or lower frequency," ETH doctoral student Manuel Eichelberger said in a press release. "That means we can use the dominant, loud notes in a piece of music to hide the acoustic data transfer."

Bits and Beats

With this technology, the researchers were able to achieve a transfer rate of 400 bits (that's around 50 letters) per second while preserving the source music. If you don't believe it, you can listen to two audio samples of the ETH Big Band below — do you hear any difference? In the first clip, a shortened URL of this press release repeats every 0.7 seconds.

A loud piece of music like this one is ideal for data transfer because it has a lot of dominant frequencies. Most pop and rock songs also work well — Queen's "The Show Must Go On" and Van Halen's "And The Cradle Will Rock" both did well in a listening test where participants were asked to distinguish between original and modified versions. More than 40 percent of participants couldn't identify the modifications, which is pretty high considering they were actively looking for suspicious sounds.

The ETH team noted that the data transfer rate realistically would be closer to 200 bits per second (the big band sample clocks in at 300 bits per second) because some repetition of data is needed to ensure accuracy and quality. Considering the tradeoff between the transfer rate, quality of data, and quality of music, this technology works best for short and simple pieces of data, like Wi-Fi passwords.

Another industry where sharing data through music could come in handy is proximity marketing. Someday, you might be able to receive special promotions or product information via music played over a store's speakers. Where there's background music and smartphone users, the possibilities are endless.

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Read about how your devices vie for your attention in the critically acclaimed book "The Attention Merchants: The Epic Scramble to Get Inside Our Heads" by Tim Wu. The audiobook is free with an Audible trial. We handpick reading recommendations we think you may like. If you choose to make a purchase, Curiosity will get a share of the sale.

Written by Andrea Michelson August 2, 2019

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