My friend just told me that they probably reproduced random generated sound. It happened by a mistake. They were playing alone on server and split their ways. When they were somewhere near end of each others network bubble one of them started to eat. Second one heard that sound. Probably there might be a problem with leaving or changing network bubbles, we hear voices from network bubble edges. They also noticed that issues with sounds are less occuring when visit area which is rarely visited by other players. It looks like surrounding sounds are not activated, for example zombies in town that were not visited.