The more I listen to NotebookLM “episodes”, the more I am convinced that Google has trained a two-speaker “podcast discussion” model that directly generates the podcast off the back of an existing multimodal backbone. The two speakers interrupt and speak over each other in an uncannily humanlike manner. I wonder whether they basically fine tuned against a huge library of actual podcasts along with the podcast transcripts and perhaps generated synthetic “input material” from the transcripts to feed in as training samples.<p>In other words, take an episode of The Daily and have one language model write a hypothetical article that would summarize what the podcast was about. And then pass that article into the two—speaker model, transcribe the output, and see how well that transcript aligns with the article fed in as input.<p>I am sure I’m missing essential details, but the natural sound of these podcasts cannot possibly be coming from a text transcript.