A similar problem with sound:

I have voice and music up until I give the Fire-eater the orders and enter the Carnival Tent. Once inside, No more voice. I'm using the CD that came with the Armed and Dangerous demo, an the updated EXE file.

Any Hints on getting the rest of the sound to work? Subtitles just doesn't work for a game like this...

It's a known problem with the A&D demo disc - it's corrupted. Try contacting LucasArts and see if they'll send you a replacement. I've heard rumors that they will. I'm sure they'd at least give you a copy of the DOS version if you mail yours in, and then you can just run it with the updated EXE available on this site or run it through SCUMMVM.

use the sound files from the DOS version if you have it