Espeak is a comapct (463KB) speech-synthesis program. It requires alsa or oss-alsa to run.
Once install, enter something like the following into a terminal window:
espeak -s 200 -v en+m5 "this is a test" <Enter>
Note: -s controls words/min; -v controls voice; en = English; +m5 is fifth male voice; there are five male, five female, whisper, and croak.
espeak --voices <Enter>
(lists all available voices and accents)
espeak -s 200 -v en+m5 -f file.txt <Enter>
(reads file.txt)
espeak can also write output to a .wav file