I have found in the last two patches sometimes a brief Zombie cry/screech occurs when I change stances or access an item.

The screech does not play completely maybe .5 seconds. Happening more in patch 0.30.113860 I have not been able to consistently reproduce it. Today when it happened I searched the entire area for a possible zombie and could not find one. It is possible there was a zombie stuck/hidden in a structure/tree.