Facebook is introducing an optional music, TV and movies recognition feature in the US for Android and iOS gadgets. If a user gives it permission to slurp up sound, it will tap into the mic on a mobile device and eavesdrop on whatevers playing in the background. The feature will then grind through its recognition machinery to identify the song, movie or TV show youre listening to. Facebook didnt say anything about listening in on background noise, including private conversations.”]
Source: https://nakedsecurity.sophos.com/2014/05/22/facebook-wants-to-listen-in-on-your-tv-and-music/