A few people have run into this, at different locations or anywhere under ground.
I don't recall if the following works for this particular problem, but it can help for crackling or stuttering sound... (worth a try)
Click on Start | Run, type in 'dxdiag' then go to the Sound tab of the DirextX Diagnostic Tool that opens. Turn down the hardware sound acceleration (I would turn it off first to see if it helps, then if it does, turn it up until the problem reoccurs then go back down a notch).