At the command line, you can make your Mac speak with
say can use different voices, read from a text file, and export the text-to-speech to an audio file.
say -v Fiona -f article.txt -o recording.aiff
System Preferences >
Dictation & Speech, you can [http://osxdaily.com/2012/06/04/add-voice-of-siri-to-mac-os-x/](add the voice of Siri), which is Samantha. Some of the voices, like Allison and Susan, sound even better than Samantha. Most of the non-American voices aren’t quite as good, but it can be interesting to have a different English accent, like Fiona’s Standard Scottish English. Cellos is, ironically, the voice in some Android phone commercials.
say -v Cellos "Droid"