@mttaggart agreed. I personally never bought the "they are listening to sell ads" stuff. They have all of your online behaviour, plus everyone in your graph, including the people you app with, and what they are looking at while talking to you, clicking on, sending you etc. etc. ad nauseam.
Why would they need to spend time and money and effort to process what you say?
And! But also completely unrelated! (gestures wildly)
Yes, there is a corpo-owned black-box device with an always-on microphone in the room. Often multiple ones. It also has fine grained location tracking, and has you logged into a gazillion tracking services. We call that a mobile phone.