Hello,
I just wanted to report that I've got the same issue that were already described here:
Luckily I was able to solve the issue with changing the audio quality to low as described by Aviat0r.
If you need any more information just let me know.
Update 2020-04-15: it turned out that there were an issue with my sound card driver. The 5.1 system were not recognized correctly: only the left and right speaker were working correctly. The center and back speakers did not play any sound and that is why there were no voices in missions etc. (they are played from the center box).
Uninstalling the device drivers and reinstalling them fixed the problem.