In the singleplayer editor; spawn a player unit and put some regular zombies and pause the game for an hour or two.
The playsounds from each zombie will queue until the point that when the player unpauses the game, a lot of sounds will have stacked and cause a potential game crash due to buffer being full.

If the sounds being played are using diag_tickTime, systemTime or other function dependent on real time. I suggest updating the playsound interval to be dependent on mission time/time since session start instead.