An increasing number of Android applications are attempting to track users without their knowledge, according to a new report.
Over recent years, companies have started hiding "beacons", ultrasonic audio signals inaudible to humans, in their adverts, in order to track devices and learn more about their owners.
Electronic devices equipped with microphones can register these sounds, allowing advertisers to uncover their location and work out what kind of ads their owners watch on TV and which other devices they own.
The technique can even be to de-anonymise Tor users.
They found that, while six apps were known to be using ultrasound cross-device tracking technology in April 2015, this number grew to 39 by December 2015, and has now increased to 234.To me, that seems like some big companies have a very unwholesome interest in my location. If somebody out there wants to know where I am that badly, I should probably hide.
The study hasn't named any specific programs, but says that several have millions of downloads and "are part of reputable companies", including McDonald's and Krispy Kreme.