This is a issue related to xaudio2.
With Proton 3.16-6 beta, adding this line WINEDLLOVERRIDES="xaudio2_7=b" %command% to this game's startup option will help. Because this game brought a native xaudio2_7.dll by itself.
Fixed in newer Proton version
proton 3.16-6x1 2018-12proton 3.7-6x1 2018-09WINEDLLOVERRIDES="xaudio2_7=b"x1 2018-12WINEDLLOVERRIDES="xaudio2_7=b" %command%x1 2018-12xaudio2_7.dllx1 2018-12
Compatibility Report
System Information
steam-705120.log
I confirm
Symptoms
Game has no audio during gameplay and in menu.
Reproduction
Example