In the most inconspicuous hustle of all, apps have increasingly incorporated ultrasonic tones to track consumers. They ask permission to access your smartphone microphone, then listen for inaudible “beacons” that emanate from retail stores, advertisements, and even websites. If you’re not paying attention to the permissions you grant, you could be feeding marketers information about your online browsing, what stores you go to, and what products you like and dislike without ever realizing it.
There are certainly legitimate uses of “ultrasonic cross-device tracking” technology. Some apps are part of rewards programs that automatically offer customers promotions when they visit particular stores. Others facilitate ticketing at events like sports games.
But plenty of apps deploy it without so clear a use case, at least as far as direct benefits for the person who downloads them. In fact, research presented last week at the IEEE European Symposium on Security and Privacy found 234 current Android applications that incorporate a particular type of ultrasonic listening technology. That doesn’t quite constitute widespread distribution, but the infrastructure to support it has landed in more and more apps every year…
…Fortunately it’s easy to monitor what’s accessing your phone, and stay in control if you’re wary of all this dog whistlin’.
Since you can’t stop beacons from emitting these frequencies around you, the best option is to reduce the chance that your smartphone can listen for them and feed data to a third party. The researchers suggest simply assessing the privileges you’ve granted your apps to make sure they make sense. Skype wants microphone access? Sure! An app for some clothing store? Probably not. Common sense works best here.
On Android 7, navigate to Settings, then to Apps. Tap the gear icon in the upper right, then tap App Permissions to see and edit the privileges you’ve granted each app. And on iOS 10 go to Settings, then Privacy, then Microphone to see which apps have requested access, and which ones you’ve granted it to…