I have completed the game recently, the only issues with audio I had was due alt-tabbing, hence I had to quit the game and start it again.
Also initially I had trouble with climbing due to fps issues, and setting timer settings to 60 fps in default xml file helped me to improve both climbing and game responsiveness overall, so you might to try it as well.

Edit note: the game I was talking about is first Risen, since you didn't mention which game you have problem with.

I assume that you talk about the first game Risen 1.

Do you have an external audio soundcard? if yes try and disable it and see if that works.

You can also go to the config default.xml file open it with notepad and change UseHardwareSounds="true" to "false"

hopefully this will help.