Here is a place to start. http://www.brainybetty.com/agent.htm

 I wonder if you could help me with a quesiton.  I cannot figuare out how to
 make powerpoint read the contents of the a slide verbally.  A co-worker has
 said that it is possible, but I have not been able to find out how.  I don't
 have a audio recording of the slide, and that is why I cannot insert an audio
 clip.  Surely Microsoft has created a verbal reader.
 
 If you know could you let me know.