Yes its notebooklm.
Did notebooklm produce the text, and then they had real people read it out loud?
This is amazing.
But also, some people talk fast.
They'd have to add some random pausing.
And fine tuning on 15 minutes of the voice you're targeting makes it sound natural
But the NotebookLM is like a recorded pod-cast, so it can think about it before laying down a track?