Hi @joshuag,
Welcome to Google Cloud Community!
To preview the new voices and assess them alongside the previous versions, you can refer to the
Google Cloud Text-to-Speech documentation, where the release notes and supported voices and languages pages provide in-depth details on the updates and available voices.
Additionally, you may want to visit the Google Cloud Blog for any announcements or updates regarding Cloud Text-to-Speech, or you could use the voices:list API endpoint to retrieve a list of all available voices and compare their features. This will help you spot any differences and make well-informed choices about which voices to select.
I hope the above information is helpful.