Converts text to speech. More information: https://ss64.com/osx/say.html.
say "{{I like to ride my bike.}}"
say --input-file={{filename.txt}}
say --voice={{voice}} --rate={{words_per_minute}} "{{I'm sorry Dave, I can't let you do that.}}"
say --voice="?"
say --output-file={{filename.aiff}} "{{Here's to the Crazy Ones.}}"