While I’m diving into the dark side of online advertising, I came across the upheaval three years ago about audio beacons being used to listen to people to, guess what, collect more personal data to, guess what, sell even more stuff to them. Here are some articles to read on that:

Does your phone listen to you for ads? (Or is it just coincidence?)

How Audio Beacons Monitor You Via Smartphone

And most importantly this paper published in 2017, in which the researchers found 234 Android applications that are constantly listening for ultrasonic beacons in the background without the user’s knowledge: Privacy Threats through Ultrasonic Side Channels on Mobile Devices (2017)

Obviously there was a lot of critique on this technique and therefore it seems to have disappeared from the advertiser’s radar. But I’m wondering whether how much of this nifty technique is currently still in use without us knowing. Just recently a friend of mine had one of those ‘they’re listening to my conversations’-moment. So far the information I can find on this are all from 2017 or still referring to the research paper I mentioned above. If you’re reading this and know more about recent use of ultrasonic or audio beacons, I’m interested!