This sound issue is absolutely annoying the piss out of me too. The sounds also seem to repeat and stutter slightly when a bunch of things happen on the screen at once. Early in a match the sound is fine, but as the game gets more hectic the sound starts to stutter and get worse over time (memory leak maybe?). This does not happen in any of my other 3 million games I have, just this one. What has me concerned is that only a few of us are reporting the problem, but the fact it only occurs in this game makes me think it's an issue of the beta (hopefully). The sound issue is so irritating that, while I am enjoying the beta a lot, I have to limit my games to only a few at a time because the popping/crackle/repeating sound gives me a headache which prevents me from REALLY delving into the beta. Instead of checking to see what may make a useful suggestion or noticing something that isn't right, I am completely distracted by the audio. I just can't win for losing. 
Here is my dxdiag info, some feedback from the devs/stardock/anybody would be greatly appreciated.
http://pastebin.com/f6152a3af
