Voice Quality of Text to Speech Programs

A screenwriter, I need my computer to read my 90-100 page scripts aloud, so I can see where to make changes. I’ve tried Final Draft Pro (a professional screenwriting program), CoolSpeech, and even SimpleText on OS 9 and 10. All the voices sound sorobotic. Can I find more natural-sounding text-to-speech voices anywhere? Thanks for your suggestions.

Bob Slaymaker
bob@bobslaymaker.com
212-558-3601