If you are using Windows XP (and higher) and a PC with a sound card, you can easily make your AutoCAD talk.
For speech-output you can use the SAPI interface in Windows and call it from AutoCAD e.g. through LISP:
(setq sapi (vlax-create-object "Sapi.SpVoice"))
(vlax-invoke sapi "Speak" "Here is your AutoCAD" 0)