What you’re probably experiencing is a conflict between NVIDIA’s sound driver that it installs with the card’s software GeForce Experience & the onboard Realtek driver. I had the same issue with on-board Realtek & GeForce GT440’s software. Troubleshot through all of the sound effects with Realtek/Windows 7 & nothing worked. I’d ended up completely uninstalling the GeForece software because every time I would disable the conflicting drivers the program or Windows 7 would automatically reset them and it was back to crackle-time.
Right click on My Computer & select “Manage” on the left side menu select “Device Manager”. In the right side list that pops up find “Sound, video and game controllers” and locate the GeForce sound driver and disable it. Try running Mirage and see if it ends your crackle. When you get to that list if you have other sound drivers for sound besides the Realtek, try disabling one-by-one to figure out where the conflict is.
To the developers:
Please bring more people to this game – I hope this helps.