If the growing proliferation of always on, always listening smart speakers in our homes is making you a little uneasy, researchers from the University of Chicago might have the answer: a wearable bracelet that jams the microphones in speakers, smartwatches, and smartphones alike.

The wearable is crammed with 24 separate transducers that emit ultrasonic waves that interfere with microphones in all directions, even if they're hidden. By transmitting white noise randomly in the 24 to 26 kHz frequency range, mics in the immediate vicinity are only able to pick up static rather than spoken words.

"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," explains the research team. "Therefore, it is critical to build tools that protect users against the potential compromise or misuse of microphones in the age of voice-based smart devices."

The wearable blasts out ultrasound inaudible to the human ear University of Chicago

While the noise of the jammer can't be heard by the human ear, it takes advantage of the design of the amplifiers inside the surrounding microphone to leave them pretty much useless as listening devices.

What's more, the natural motion of the hand while the bracelet is being worn minimizes blind spots – areas where the ultrasound broadcasts overlap, potentially canceling each other out. In other words, a wearable jammer is more effective than a stationary one.

The wearable even works if microphones are covered by paper or cloth, and in a field test, users reported feeling a greater sense of privacy while wearing the bracelet. It's only a prototype for now, but it appears to be an effective one.

As you can see from the images and video below, the wearable isn't something that can be practically worn, at least not without attracting a lot of strange glances. Further down the line though, once the electronics are miniaturized, these sort of privacy-protecting gadgets could become as popular as the devices they're designed to interfere with.

"We believe our wearable provides privacy in a world in which more and more devices are constantly eavesdropping on our conversations," conclude the researchers.

A paper on the bracelet is being presented at the 2020 CHI Conference on Human Factors in Computing Systems and the video below demonstrates the technology

Wearable Microphone Jamming

Source: University of Chicago