Greetings,

Unfortunately, none of the espeak variants that come with nvda are optimized for rapid speech.  Some time ago, a friend of mine and I developed one just for that purpose.  We called it bullet.  We did not share it with anyone because it served our purposes and we did not have the time to beta test it on a wide variety of systems or with languages other than english.

We live in the U.S. We use the english (America) voice.  We tested it with all of the english voices.

If you are an english speaker and you can stand the english (america) voice, we would be willing to share our Bullet epeak variant with you.

I usually run at 40% with rate boost checked.  I set pitch to 40 and inflection to 75.

I can’t give you an estimate on words per minute but it is several hundred.

I have tested it up to 70% with rate boost checked and it doesn’t seem to distort.

I listen with headphones or a set of wired speakers with a separate woofer but the variant sounds good on my laptop speakers as well.

Let me know if you would like to try it out.

George

You get used to it. Words don't run into each other, you can recognize them as you do at slower speeds. Default speeds are too slow and inefficient for navigating around. You can easily go beyond default speeds, how high, that is a question. And, perhaps depends from person to person.
By flutter I mean, a kind of shiver in the voice or the voice getting more robotic than usual. In E-speak it occurs at 100% and at alll boost mode rates. It is still comprehensible, just annoying.
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Regards,
Sociohack