Ultrasonic cross-device tracking. Audio "beacons" can be embedded into television advertisements, like radio beacons. When picked up by smartphones, allow behavior of users to be tracked - Upgoat

Ultrasonic cross-device tracking. Audio "beacons" can be embedded into television advertisements, like radio beacons. When picked up by smartphones, allow behavior of users to be tracked
submitted by Conspirologist to Interesting 1 dayJun 18, 2025 03:55:43 ago (+2/-1) (en.wikipedia.org)
https://en.wikipedia.org/wiki/Cross-device_tracking

This is why phones with the Facebook app installed have shorter battery life. That shit is constantly listening for those tones.