Let the mac speek

mac os x has a nice built in feature:
the command line tool "says" can convert text to audible speech

Here are some samples from the man page:

$ say Hello, World
$ say -v Alex -o hi -f hello_world.txt
$ say -o hi.aac Hello, World
$ say -o hi.aac --data-format=alac Hello, World.
$ say -o hi.caf --data-format=LEF32@8000 Hello, World