distant cedar
Since the update, if you start going ham on the zombies... As in spamming attack with a machete type weapon with frost mod attached (haven't tried yet with other mods or with a plain weapon), almost all audio cuts out for a few seconds and then comes back in.
To me it seems like the game had its audio channels count reduced, which is now causing this kind of audio bug, where there's a lot of things going on at the same time.