The narration was created using 'espeak' to convert a text-file to a
WAV within a terminal like so:

espeak -f '/path/to/file.txt' -p 10 -s 130 -v english_rp -w output.wav

But having that said, you may be MUCH better off using an online TTS
service as far as quality goes. I have yet to find a text-to-speech
desktop program for GNU/Linux that does not sound like a robot.

Make sure to not have punctuation touching any "--", such as "!--"; 
otherwise, 'espeak' will say the word "exclaimation,"  for example.
