If you have multiple audio devices (e.g. Realtek HD, Sound Blaster, Nvidia Geforce, ...) make sure you disable all the ones you're not using. For instance, if you're outputting audio through your graphics card, disable the integrated sound chipset in the device manager and bios. I don't know if that will actual fix the issues in this game, but it's a recommended practice for gaming in general as multiple active sound cards can result in issues in several games.
Also make sure the in-game audio settings are setup correctly. If you stereo speakers or headphones, the in-game dynamic range has to be set to stereo/headphones. The home theatre setting is reserved for surround sound setups.