https://phys.org/news/2018-05-ultrasound-firewall-mobile.html

The SoniControl project of St. Pölten University of Applied Sciences has developed a mobile application that detects acoustic cookies, brings them to the attention of users, and if desired, blocks the tracking. The app is thus, in a sense, the first available ultrasound firewall for smartphones and tablets. "The most challenging part of developing the app was to devise a method that can detect existing ultrasound-transmission techniques reliably and in real time," said Matthias Zeppelzauer, head of the project and senior researcher in the Media Computing research group of the Institute of CreativeMedia/Technologies at St. Pölten UAS.

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