It was an ad partner’s pitch deck, not much to do with Facebook itself. And it didn’t really explain how it would be listening anyway.
Besides, if they were recording, processing and / or transferring audio, that would mean there’s data usage, battery usage, etc - stuff that’s easy to prove.
The truth is a lot simpler (and scarier) and you will find that in the links I provided.
Of course a researcher is never sure something is 100% ruled out. That’s part of how academic research works.
My eagerness stems from being tired of anecdotes presented as evidence supporting a weird privacy conspiracy. This takes away from the actual issue at hand, which is your digital footprint and how your data is used.