The rise of voice command technology like Alexa and Google Assistant is opening the door to a new type of security breach. Consumers are becoming increasingly nervous with the fact that these interactive devices are, by default, always listening, recording, and possibly saving sensitive personal information. Is there a way to protect users from misuse of microphones?
University of Chicago engineers have developed a wearable microphone jammer that is capable of disabling microphones in its user’s surroundings, including hidden microphones, reports SAND Lab at University of Chicago.
The engineers: Yuxin Chen, Huiying Li, Shan-Yuan Teng, Steven Nagels, Zhijing Li, Pedro Lopes, Ben Y. Zhao and Haitao Zheng, built their device based on a recent exploit that leverages the fact that when exposed to ultrasonic noise, commodity microphones will leak the noise into the audible range. Moreover, the device exploits a synergy between ultrasonic jamming and the naturally occurring movements that users induce on their wearable devices (e.g., bracelets) as they gesture or walk. These movements can blur jamming blind spots and increase jamming coverage, according to the researchers. Lastly, the wearable bracelet is built in a ring-layout that allows it to jam in multiple directions. This allows the jammer to protect against hidden microphones.
Recently, researchers have shown that ultrasonic transducers can prevent commodity microphones from recording human speech. However, these devices have limitations: 1) They are heavily directional, thus requiring users to point the jammer precisely at the location where the microphones are. 2) They rely on multiple transducers that enlarge their jamming coverage but introduce blind spots locations were the signals from two or more transducers cancel each other out.
As the new device is worn as a bracelet, it leverages natural hand gestures that occur while speaking, gesturing or moving around to blur out the aforementioned blind spots. Furthermore, by arranging the transducers in a ring layout, the new wearable jams in multiple directions and protects the privacy of its user’s voice, anywhere and anytime, without requiring its user to manually point the jammer to the eavesdropping microphones.
“We confirmed that an ultrasonic microphone jammer is superior to state-of-the-art and commercial stationary jammers by conducting a series of technical evaluations and a user study. These demonstrated that: our wearable jammer outperformed static jammers in jamming coverage; its jamming is effective even if the microphones are hidden and covered by various materials, such as cloths or paper sheets; and, in a life-like situation our study participants felt that our wearable protected the privacy of their voice,” the researchers said.