Speak
From Linuxintro
Sometimes you want your computer to speak text over its sound system. Maybe this is for accessibility reasons or just for fun. Different applications are available to do that:
Applications
Example: festival
You need the software festival. In the following example your computer will say "You are a cool Linux guru":
duffman:~/speech_tools # festival Festival Speech Synthesis System 1.95:beta July 2004 Copyright (C) University of Edinburgh, 1996-2004. All rights reserved. For details type `(festival_warranty)' festival> (SayText "You are a cool Linux guru")