Computer science professors at the University of Chicago (UChicago) designed and 3D printed a wearable device prototype that impedes microphones in the vicinity from eavesdropping on conversations.

Aptly dubbed the “Bracelet of Silence”, the device features 24 speakers that emit 24k-26kHz ultrasonic signals, effectively jamming nearby microphones. While being inaudible to human ears, the device takes advantage of non-linearities in the mic’s amplifier to render recordings unusable.

Smart speakers like Alexa and Siri are among the devices that are blocked from listening in to your conversations by this device.

“Despite the initial excitement around voice-based smart devices, consumers are becoming increasingly nervous with the fact that these interactive devices are, by default, always listening, recording, and possibly saving sensitive personal information”, the researchers stated in their press release.

While the bracelet is not the first jamming device invented, previous devices were heavily directional, requiring users to point the jammer precisely at the location where the microphones are.

By arranging the transducers in a ring layout, the researchers state the wearable device jams in multiple directions and protects the privacy of its user’s voice, without requiring its user to point the jammer to the eavesdropping microphones manually.

As of now, the bracelet is in a prototyping stage and has not been made for mass production. However, the research team is confident that it would only take around $20 to manufacture it. They are currently in talks with interested investors to commercialize it.

You can download the Arduino codes for the signal generator and 3D printing models on GitHub.

(Source: University of Chicago)