There was a story going around a while back that claimed that one of the big Silicon Valley companies was doing this: Bought TV ads that had such audio clues, t

There was a story going around a while back that claimed that one of the big Silicon Valley companies was doing this: Bought TV ads that had such audio clues, then eavesdropped on you to detect them. I don't recall if it was Facebook's mobile app or Alexa that supposedly did the listening. A very quick web search didn't uncover anything concrete, but I'm somewhat certain I didn't dream this.