Install mimic:
pip3 install mycroft-mimic3-tts[all]
You can get a sample of the available voices at:
Download the voices:
mimic3-download 'en_US/*'
mimic3-download 'en_UK/*'
List the available voices:
mimic3 --voices
Use mimic from the command line:
mimic3 --voice en_US/cmu-arctic_low#slt "Hello, World!" > output.wav
Convert a text file to speech:
cat text.txt | mimic3 --voice en_US/cmu-arctic_low#slt > output.wav