I was running through Elektro, then I suddenly heard voices (no other application was in background, so it was DayZ!). They were cut off, like someone speaking with a reaaaaally laggy/slow connection. After I alt-tabbed out a few times, the voices were gone and I was not able to reproduce that.
As this was a german server and the voices were german too, I guess it could be that I heard the voices globally, as there were no people around me, especially no group of people talking.