Dark Souls 3 (374320) audio corrupts (and stays corrupted) after a while

Compatibility Report

• Name of the game with compatibility issues: Dark Souls 3
• Steam AppID of the game: 374320

System Information

• GPU: GTX 1070
• Driver/LLVM version: Nvidia 410.73
• Kernel version: 4.18
• Link to full system information report as Gist: https://gist.github.com/Leon422/15f1906b04e48ab3d03e6b946e008979
• Proton version: 3.16-4 beta AND 3.7-8 (both tested)

I confirm:

• that I haven't found an existing compatibility report for this game. (not for this issue anyway)
• that I have checked whether there are updates for my system available.

Symptoms

After playing for a while the audio gets corrupted and garbled, and stays that way until I close and re-open the game. Sometimes it happens after 5 minutes and sometimes it takes like 30 minutes. The game seems to stutter when this kicks in.

Reproduction

Play the game for a while.

Note: I'm using an USB headset (HyperX Cloud 2). This headset is plug and play, it doesn't need any kind of special drivers, it's just a generic USB sound card. It doesn't give me problems with any other game, not even other Proton games.

No source files or tests are identified. First reproduce the corruption with the listed Proton versions and USB headset, then rerun with PROTON_LOG=1 and attach the generated Steam AppID log; done means identifying a reproducible cause and confirming that audio remains clear during extended play.