While the sound can’t be heard by the human ear, nearby tablets and smartphones can detect it. When they do, browser cookies can now pair a single user to multiple devices and keep track of what TV commercials the person sees, how long the person watches the ads, and whether the person acts on the ads by doing a Web search or buying a product.
.. “and the ad industry wonders why we hate them” … (not my original quote – but definitely my sentiment – the words of Shawn King @ The Loop.
That is a screen grab of the behind the scenes activity tracked by Ghostery around the URL of the New York Post. A Lot of other sites have exactly the same activity. — Read on, but THAT’S why I run content blockers.