The commonly reported solution to solving audio glitching in DD is to set processor affinity to 1, usually using RunFirst.

I found that when I did that on my rig, the intro movie would go all glitchy and gameplay, especially when running around, would slow down quite a lot. This turned out to be because the single CPU core the game was now allowed to use was maxed out at 100%. My CPU is no slouch - it's one of Intel's latest, the i5-2500K running at 3.4GHz. The CPU load was high because I was running at 1680x1050. Backing down to 1280x1024 reduced the CPU load considerably.

So I decided to run without CPU affinity just to see how often the audio glitching occurred. It took awhile, but after several days of playing, I finally found an area where it started happening. I exited the game to windows, then reloaded the game from my last save point, entered the problem area and the audio glitches started again.

I found this thread in which Stuff talks about Realtek's PC Beep being a cause of the problem. I happen to have Realtek onboard sound, but the latest Realtek drivers have removed the PC Beep slider so there seems to be no way to disable it.

Some creative googling later, looking for ways to disable PC Beep led me to threads about Microsoft Security Essentials' RealTime Protection causing DPC latency.

I did all that info searching on another computer, and had not quit or restarted the computer I was running DD on, so I exited the game to Windows again, opened MSE, turned RealTime Protection off then back on again, restarted DD and the audio glitching was gone!

Just thought players and devs would want to know about this.

Edit: found a way to disable the internal speaker which may or may not be causing this problem, whether or not you have an internal speaker. I think this does the same thing as the PC Beep slider that is now missing from RealTek Sound Manager:

If you're running Microsoft Windows you can disable the Internal speaker or PC speaker by following the below steps.

1. Open Device Manager
2. In Device Manager click View and click "Show hidden devices"
3. This should make "Non-Plug and Play Drivers" visible in Device Manager.
4. Expand Non-Plug and Play Drivers by clicking the plus and double-click Beep.
5. Within the "Beep properties" window click the Driver tab.
6. Under the driver tab if you wish to temporarily disable this device click the Stop button. If you wish to permanently disable this device under the Startup Type select Disabled.

More testing required to see if this fixes audio glitching in DD.

Thanks for posting your solution, always appreciated. . . . =)

I tried this solution on my single-core netbook. Unfortunately, it didn't help; I got a burst of static as soon as the main menu appeared, and just standing in the attic at the beginning of the game got audio glitches.

So, it may be a fix in some circumstances, but it's not the end solution.