
I have both of these in my Alpha Centauri.ini:
ds3d=1
eax=1
The program put them there, I have not touched them.
What follows is stuff I've culled from several forums wherein people have asked for help with issues similar to those raised in this thread. I am not a techie by any stretch of imagination

I'm only passing along what others have suggested. If none of this is any help

I'm sorry.
For those with distorted sound:
Most often, the first thing I've read in responses to this issue in several forums is: "Are your audio card drivers updated?" If that is all set, you can try adding either or both of the two lines I noted above (both were already mentioned by Straybow and Anunikoba) anywhere in the first section under [Alpha Centauri]. In mine they are the third and fourth lines. Try the various possible combinations until one works: (0/0), (0/1), (1/0), (1/1). Also try with one or both deleted. If none of these changes helps, put everything back as it was before you started. Something else is the cause. You
did remember to make note of the original settings, right?
For those with volume issues:
A few lines farther down are these four entries:
Main Volume=127
Voice Volume=127
Music Volume=63
SFX Volume=127
These are all accessible from within the game in the Audio Preferences part of the Main Menu. 127 is the maximum. I have the Music down because I usually have other tunes playing in the room but I still want to hear the event-triggered themes. If these are in your .ini, are any of them set to zero?
A related item which may or may not be of interest to anyone:
The other day I took the case off my system to clean out the cobbies and fuzz - something I've been in the habit of doing a couple times a year. I unplugged my headset/microphone before opening the case because the cord was in the way. I didn't bother to reconnect it when I was done because I haven't used it for at least a year. Now
all the sounds from the speakers are cleaner than with the headset attached, but the SMAC in-game sounds are most noticeably crisper and louder