This experimental bracelet stops smart speakers from eavesdropping

Smart speakers like the Google Home and Amazon Echo have a button that cuts off the microphone. They also only listen when their wake word is spoken, but mishearings do happen, so you could be unlucky enough that your most private words are uploaded to a cloud server somewhere.

But a prototype wearable from the University of Chicago shows how fears of eavesdropping smart speakers could theoretically be a thing of the past. 

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The chunky bracelet isn’t exactly a looker at the moment, but it serves its main purpose. The band has 24 speakers that broadcast ultrasonic waves inaudible to humans (though possibly in the frequency of children and dogs) that cover up recorded chatter with a blanket of white noise. 

While the underlying theory isn’t that different from conventional sound jammers, this one has a few key advantages. Firstly, it’s portable, meaning that your privacy is protected wherever you go, even if you don’t see a visible microphone – which paranoid types will appreciate given the sheer number of mic-enabled devices the average person carries these days.

Secondly, it’s omnidirectional. Existing jammers rely on users pointing the jammer at the microphone. The 24 speakers on the bracelet fix this problem quite neatly.

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Thirdly, and to get a little technical, conventional jammers suffer from blind spots. As the researchers explain: “they rely on multiple transducers that enlarge their jamming coverage but introduce blind spots locations where the signals from two or more transducers cancel each other out.” 

If a microphone falls in one of these gaps, then the recording will be unaffected. But thanks to this jammer’s bracelet form factor, it “leverages natural hand gestures that occur while speaking, gesturing or moving around to blur out the aforementioned blind spots.” As the graph below shows, this makes it more effective than other alternatives:

While this is a prototype that, as the New York Times explains, came about because two married computer scientists had differing views over the creepiness of their home office’s Amazon Echo, it could eventually become a real product. The report claims “a handful of investors” have asked about commercialising it, and the researchers say it could be done for “as little as $20” – or around £15.

If that ever happens and they end up being quite popular, regular phone calls in public places might become a lot more tricky to conduct…