Convert text to speech. More information: https://keith.github.io/xcode-man-pages/say.1.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 --voice=Zosia "Litwo, ojczyzno moja!"
say --output-file=filename.aiff "Here's to the Crazy Ones."