According to an official complaint filed by the CDT, the privacy watchdog is tattling on advertisers like SilverPush, Drawbridge, and Flurry, online companies that deploy ads that squeal high-frequency sounds from the devices they’re loaded on.The CDT says that these ultrasonic sounds scan the room for other devices like phones, tablets, TVs, computers, and wearables, effectively tying their presence to a browser cookie, an IP, and indirectly a user.Whenever the device owner accesses a page with an ad from these companies from other handsets, the ad network will be able to recognize them based on the device’s fingerprint in their database and the presence of some tracking code left behind by the ultrasonic sounds emanated from previous visits via other nearby devices.

What a massive, blatant invasion of privacy. I want to know what apps embedded this software so I know never to trust the developers ever again.

Time to revoke the use of my iPhone and iPad’s microphones to all apps methinks.

Source: High-Frequency Sounds Embedded in Ads to Track Users Across Devices