Per the Kiplinger letter:

Did you know that marketers are using cross-device tracking to learn all about you? They connect and track every Internet enabled gadget that you and others use every day. Because of this tracking Uncle Sam is considering possible regulations.

The Feds want to stop another new marketing tactic: The Federal Trade Comm. has issued cease-and-desist letters to app developers that are using your smart phone to pick up sounds, inaudible to humans, emitted by TV ads. The detailed personal tracking comes without the viewer’s knowledge or consent.