Too late to edit, but to any one who needs "convincing" of the flexibility of a formant synthesizer, you should 1) play with Pink Trombone[1], a Javascript formant synthesizer with a UI that lets you graphically manipulate a vocal tract, and 2) have a look at this programmable version of it[2]

[1] https://dood.al/pinktrombone/

[2] https://github.com/zakaton/Pink-Trombone

Thanks for those links, that's superb. Sounds surprisingly like the "Oh long Johnson" cat - https://www.youtube.com/watch?v=kkwiQmGWK4c

What a fun toy! But I mostly get sounds of a drunk man who tries to say something but cannot.

Check out the videos in the second link - it gives some better examples of what you can do with it.

Funny that the Pink Trombone website does not work with screen readers.

It's entirely visual in that it is a graphic of a vocal tract where you can move the tongue and shape the mouth, so in that form trying to make it do anything with screen readers would mean basically doing what the second link does, and create an API for it and hook the backend up to an entirely different UI.

The videos on the other link does show that the guy who has done that API has done stuff to the UI to allow interfacing to it in non-graphical ways, but sadly I don't see any online demos of those alternative user interfaces anywhere, which is a great shame. Sadly it doesn't look like the videos are very accessible either, as they're mostly demos with no commentary about what is going on on the screen, without which they're mostly just random sounds.

Yeah, Pink Trombone is awesome[0]. :D

Thanks for the link to the programmable version--I don't think I'd been aware of that previously...

[0] And, from personal experience, also rather difficult to "safely" search for if you don't quite remember its name exactly. :D

That reminds me of Google's blob opera: https://artsandculture.google.com/experiment/AAHWrq360NcGbw