A say example:
Using terminal navigate to the directory where the source file is at.
say -v Ava -o "audio_file_created.aiff" -f "file_to_read.txt"
-f tells the program to read the file following in parenthesis
-o tells the program the output file to record to.
-v is the voice to use
Personally I use another app to convert to mp3 since that is small and fairly ubiquitous.
To use wave as the output (-o) navigate to the source directory. Then add –data-format=LEF32@8000 after the output file.
say -v Ava -f "Findings_about_Research-R2_JGnKS.txt" -o Findings_about_Research-R2_JGnKS.wav --data-format=LEF32@8000
This sounds lousy though. I prefer to use Quicktime 7 and convert.
More can be learned from a web search, but this is a note to self.