Android Phone Apps listening for sub-audible sound signals can start monitoring user’s activities and then reporting said garnered privacy violating data back to servers run by the App authors for advertising data purposes. . . or perhaps other more malicious purposes. NOT GOOD. PING for your list member’s awareness.
If they catch words like “right wing”, “christian”, “conservative”, “pro-life” on your phone I’m sure you’re added to a government black list they are just waiting to use.
This was inevitable. Once everyone wanted their phone to be their miniature home computer as well as dgital camera, we lost any hope of privacy left to us. When I was an Assembler language programmer at the dawn of the PC era, I saw this coming. Just a matter of time until chips would be improved to work faster and store more data.