Often I'll walk by a cave and I'll hear this weird moaning type of sound (It's kinda hard to describe) I know its not a zombie, skeleton or spider so it freaks me out every time >.>
Also I have encountered a mob spawner but didn't hear it make this noise but it's the only thing I could think of that might make it... --- Official Tempest of the Tempest Board http://www.gamefaqs.com/boards/948715-tempest
Err i think i know which noise you are talking about... There was a big topic about it on the forums. Everyone was saying its either a noise you hear around caves, or when in water. Its probably just zombies though, they make a few different noises.
--- id rather reign in hell, than serve in heaven. http://i833.photobucket.com/albums/zz258/dazbuzz2/sig/213.jpg
when you are near an area that is dark enough for monsters to spawn (whether it is visible or not or large or not) the game will randomly play a random "creepy sound". that's probably what you're hearing.
--- "Yes, I am a hypocrite." - DeepsPraw http://www.ukresistance.co.uk/blueskybanner2.gif