In her own testing, Professor Burns said that after discussing certain topics within earshot of her phone, she would then see ads relating to those topics on Facebook.
"This is not true. We show ads based on people’s interests and other profile information – not what you’re talking out loud about," Facebook said.
Facebook says it accesses your phone's microphone if you have given our app permission and if you are actively using a specific feature that requires audio. This might include recording a video or using an optional feature Facewbook introduced two years ago to include music or other audio in your status updates.