alt Hacker Newsnielsen's ACR method is embedded into millions of devices and vendors. No need for a microphone, it's processing the audio signal being sent out. A microphone would be a wasted conversion..
(your car infotainment also likely has nielsen tech in it most likely, as they bought arbitron and gracenote)
Notably, the TV was caught making audio recordings and transcripts of conversations, and sending them to LG, independently of all this.