What kind of sound card do you have?
Here are some things you can try anyway:
1) In the sound setup, play around with the music device settings until it works. General MIDI works for me.
2) Try the thing in 'real' DOS, after loading any DOS drivers you might have for your sound card.
3) Get rid of the sound fix and mess about with the settings a bit more! Without the "fix", I can get full voices and music after a bit of mucking about... with the fix, I can only get the voices as you describe.
And if you're running Win2000 or XP, check out the "quick and easy fix" that was posted on Mojo
a few days ago.