Many people seem daunted by the fact that Festival uses Scheme as its scripting language and feel they can't use Festival because they don't know Scheme. However most of those same people use Emacs everyday which also has (a much more complex) Lisp system underneath. The number of Scheme commands you actually need to know in Festival is really very small and you can easily just find out as you go along. Also people use the Unix shell often but only know a small fraction of actual commands available in the shell (or in fact that there even is a distinction between shell builtin commands and user definable ones). So take it easy, you'll learn the commands you need fairly quickly.