Using Music to Spy on Someone’s Physical Movement

Cameron Coward
Aug 24, 2017 · 2 min read

Most people are familiar with the concept of sonar, which can map environments and track movement by measuring the reflections of sound waves. Active sonar technology (which emits sound and processes the echo) was first patented in 1913, and was inspired by the desire to avoid another tragedy like what happened to the Titanic. The tech quickly evolved, and now it’s used for everything from military surveillance to autonomous vehicle guidance.

The researchers tested CovertBand using a Samsung Galaxy S4 smartphone hooked up to a portable speaker. (📷: Dennis Wise/University of Washington)

However, what most people don’t realize is how sonar can be used to covertly spy on them. Sonar doesn’t require any large or obvious equipment, just a speaker and a microphone. In the modern world, we’re surrounded by devices that are capable of being used for this purpose — you probably have one in your pocket right now.

A team of computer scientists at the University of Washington have even developed a method for adding a sonar signal to music for hidden surveillance. The technology, called CovertBand, can be implemented on just about any connected device that contains a speaker and microphone; your smartphone, computer, smart TV, and smart assistants can all be hijacked for this purpose. A known sound wave pattern is added to music playing from the device, and the microphone picks up the changing echoes of that known wave.

CovertBand can remotely transform a smart device into an active sonar system, using its microphones to transmit a repeated audio pulse and its speakers to collect spatial information on how those pulses are reflected due to the repetitive motions of users. (📷: Dennis Wise/University of Washington)

Using just that information, the researchers were able to detect and even map someone’s movement within a room. They could even monitor the person’s motion through wood doors, drywall, and windows. Of course, they intend their project to simply highlight the potential for invading someone’s privacy using the tech, and don’t plan to use it themselves. But, it’s certainly one more privacy concern to worry about in today’s world.

Hackster Blog

Hackster.io, an Avnet community, is the world’s largest network for hardware & software developers. With 1 million members and 17,000+ projects, beginners and professionals can learn and share how to build robotics, industrial automation systems, AI-powered machines, and more.

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Cameron Coward

Written by

Author, writer, maker, and a former mechanical designer. www.cameroncoward.com @cameron_coward

Hackster Blog

Hackster.io, an Avnet community, is the world’s largest network for hardware & software developers. With 1 million members and 17,000+ projects, beginners and professionals can learn and share how to build robotics, industrial automation systems, AI-powered machines, and more.

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