I've done this..... it requires the microsoft text-to-speech control. The package (if you google, you should be able to find it) has controls to go in both directions (text to speech, so the computer can talk to you, and voice recognition, so you can talk to it, and it can respond).
I've done that..... it didn't uh, work as well as one would hope. I always thought a slick thing to do would be to build an IRC client where you can tag a user.... and then when they are tagged, whatever they type will spoken (text2speech) through the speakers..... This way you don't have to flip back and forth all the time.
Batch files had no means of playing sound through the speaker.... QBasic, debug, or some other file could have been called by the batch file to spawn the app that plays a text to speech, but batch files themselves are not a language, and lack the kind of power required to perform text to speech.
Beyond that, this is a Visual Basic Forum, and if there was/is an external app that needed to be spawned, VB could do it all by itself. Now, if you could somehow show the VB code to create your super-batch file, by all means, I'd love to see it, and so would many others... but just do me a big favor, and try to keep the post relevant and helpful to the forum/thread. Thanks Bud.