This was my reply to the same question asked a while ago :-
Too fix the crackly sound you sometimes get in ut, when loading in XP, open advanced preferences (type preferences from console), open audio section, change effectschannels too 8, change latency too 60, restart UT.
The problem is caused by windows XP hd prefetching algorithm loading ut modules faster than the sound subsystem can initialise properly - hence it only occuring when ut loads from system cache, worked for me and many others
also another reply by zippythepinhead was made he said this :-
I fixed it by disabling DirectSound within Unreal Tournament through the console. I haven't had any sound issues since
The issue worked for me and the user i hope it does the same.
Ep, glad to see you come back and tidy up...did want to ask a one day favor, I want to enhance my resume , was hoping you could make me administrator for a day, if so, take me right off since I won't be here to do anything, and don't know the slightest about the board, but it would be nice putting "served administrator osnn", if can do, THANKS