Apple has built extremely good audio book synthesis: https://authors.apple.com/support/4519-digital-narration-aud...
https://9to5google.com/2020/12/03/google-auto-audiobook/
https://www.publishersweekly.com/pw/by-topic/industry-news/a...
https://support.google.com/books/partner/table/10957334?hl=e...
The fragment for "Jackson" has a very clear robotic distortion about 10 or 12 seconds in, for example. Madison and Helena are better, though they have weird pacing issues.
I couldn't stand to listen to these voices for a long time. With how good 15.ai's female voices are (when they come out with new versions), I must say I expected better.
This is not realtime speech to text as we think of it generally.
Direct link to GitHub: https://github.com/neonbjb/tortoise-tts