I've seen stories where people could not explain why they were suddenly seeing certain ads in their feeds, and they thought Facebook had recorded some keywords

I've seen stories where people could not explain why they were suddenly seeing certain ads in their feeds, and they thought Facebook had recorded some keywords from a conversation. For example one guy had a buddy who had recently purchased a certain motorcycle, and all of a sudden he started seeing ads for that motorcycle. But... really there's a simpler explanation than the microphone. Although of course it doesn't by itself rule out the microphone being used. Facebook can just see when you are in the same location as some other people, and see what things those other people are into, and then signal whatever ad networks that you might also be a prospect for those things. Visit your buddy and see his new bike? Start getting ads for the same bike. No audio needed, just location services and some posts on FB from your buddy about his motorcycle. And there are other sensors beyond that. A lot of things are possible once the user has granted permission for use of various inputs. Also if it is the microphone as the story suggests it could be in some cases, the evidence for it being any one particular app is thin. There are other apps that get granted microphone access by users all the time, and some of them should be looked at, not just Facebook. Not to defend Facebook here, but the net should be cast wider than just one app, even if the ads are appearing on Facebook, which itself is perfectly capable of gleaning interest information from multiple sources including other ad networks fed by other apps.