She sounds younger to me, but very natural sounding.

Will be interesting to see how Siri on Home Pod works out.

Yes. And the way it answers some questions, it also seems to be going for a more casual, enthusiastic sort of vibe. It wasn't clear to me to what degree the changes apply outside of the female American voice.

She does sound younger. I think it's because the 's' is more... lispy. She sounds a bit more valley-speak-ish, although that could just be a result of sounding more natural of course.

I'd love to have my Instapaper articles read to me in that TTS voice.

Hopefully it gets ported to MacOS's say CLI utility. I typically use that with `pbpaste | say` to read my articles.

I would assume that the OS X TTS engine is the same as Siri's as it would be available in High Sierra.

Is the one in Sierra different from Siri in iOS 10?

> I would assume that the OS X TTS engine is the same as Siri's as it would be available in High Sierra.

Nope, macOS uses a different set of voices for TTS, which are named differently as well. They work offline and are nowhere as good as Siri.

I haven't needed to use Siri on my Mac, but presumably that's using the same stuff as iOS?

We're talking about the MacOS TTS engine accessible via the `say` utility and (I believe) accessibility tools, not Siri which is presumably a different software stack and which uses remote processing.