Facebook patents system that can use your phone's mic to monitor TV habits

System would allow Facebook to identify what adults and children are watching based on ambient noise

Facebook has filed to patent a system that can remotely activate the microphone on someone's phone using inaudible signals broadcast via a television.

The patent application describes a system where an audio fingerprint embedded in TV shows or ads, inaudible to human ears, would trigger the phone, tablet or long-rumoured smart speaker to turn on the microphone and start recording "ambient audio of the content item". The recording could then be matched to a database of content to allow Facebook to identify what the individual was watching - like Shazam for TV, but without the individual choosing to activate the system.