A “shield” device against microphones located in the user’s environment (including hidden microphones) was developed by researchers from the University of Chicago.
This hand-worn device, referring to a bracelet, is based on the fact that when exposed to ultrasound, most commercially available microphones leak sound into the audible spectrum. In addition, as the researchers note, the device exploits a synergy between ultrasonic interference and the physical movement of wearable devices used by users (eg bracelets) as they walk or gesture.
Researchers have shown in their work that these movements can counteract / compensate for the “blind spots” of interference, but also increase the range of interference. Additionally, this bracelet is designed in a way that allows for multi-directional interference, thus protecting the user from microphones that are not visible.
The creators of the device stress that consumers are becoming more suspicious and nervous about the “smart” electronic devices that are activated and operated by voice, because they are able to “listen”, record and possibly store personal information. In this context, they have taken advantage of the above-mentioned ultrasound phenomenon, which can prevent the recording of human speech from commercially available microphones.
“Although these ultrasound signals are not perceived by human ears, they leak into the audible spectrum when “caught” by microphones, producing an interference signal inside the microphone circuit, which causes a problem with voice recording.”
they note relatively, adding however that such devices are largely directional and that they are based on multiple transmitters, which may leave “blind spots”. Therefore, this device converts the ultrasound jammer into a bracelet and utilizes the natural movements of the hand during speech, movement, gestures, etc. to cover these “blind spots”, protecting the user without having to “target” the microphones.