These things are highly nuanced. The amount of tweaking and finessing that goes on under the hood for specific scenarios can change outcomes quite a lot. And

These things are highly nuanced. The amount of tweaking and finessing that goes on under the hood for specific scenarios can change outcomes quite a lot. And from a product perspective, it can be taken quite far - for example, most of the 'common' things Siri says are not synthesized, it's literally are recording of the voice over artists. The more arcane stuff is synthesized. It's always comparing apples to oranges to bananas unless you really know what they're doing, even then it's hard.