More Android phones than ever are covertly listening for inaudible sounds in ads

Dan Goodin:

Almost a year after app developer SilverPush vowed to kill its privacy-threatening software that used inaudible sound embedded into TV commercials to covertly track phone users, the technology is more popular than ever, with more than 200 Android apps that have been downloaded millions of times from the official Google Play market, according to a recently published research paper.

As that use inaudible sound to link your phone, TV, tablet, and PC
As of January, there were 234 Android apps that were created using SilverPush’s publicly available software developer kit, according to the paper, which was published by researchers from Technische Universitat Braunschweig in Germany. That represents a dramatic increase in the number of Android apps known to use the creepy audio tracking scheme. In April 2015, there were only five such apps.