[Environment]
Laptop MSI GT729
integrated soundcard or using Logitech Z10 speakers.
system: Windows 7 HP
Using both - integrated soundcard with build-in speakers or usind Logitech Z10 speakers I have found some distorions and very annoying. I wanted very much play this again and I was not able due to sound problems. Strange thing is that music plays quite well, only sound efects, voices are most affected. as I remember I havent this problem on Vista.
Does anyone has similar problem? Is there any solution?
[Edit]
I have found simple solution, but I'm not happy with it:
1. I have opened Unreal.ini
2. and set LowSoundQuality=True (before wa False)
It helps a bit. voices are no longer disorted. I will test it further so if there are some more problems I will report it here.

If I recall, the fix for this is to adjust the audio latency. It's a parameter in the unreal.ini file. Look in the Unreal installation directory, there should be a System directory in there. In that system directory is the unreal.ini file.
Under the [Galaxy.GalaxyAudioSubsystem] there is a line that reads "Latency=40". Change the 40 to 110 or so, save the file, launch the game, and see how it is. You can turn audio quality back to High as well.

Why not try installing the Old Unreal patch and testing out the OpenAL and FMOD sound systems instead of the default Galaxy Audio sound system?
That might just work.

I had this same problem.
Originally I installed game in Windows XP, where all worked fine as is, then changed to Vista, and didn't reinstall game, instead simply used the old Unreal installation. In Vista I encountered these audio problems (which also caused some graphical errors somehow).
The latency value change fixed the problem for me, now its back to normal again.