I was in Dagoth Ur, Inner Facility. When i attacked an acended sleeper that made a were wolf audio! I tried it again and it still did it. What's up?

They all do that, as far as I know. They've always done it with me anyway... it is kind of creepy, though.

It could be a conflict with Bloodmoon I guess, but I don't remember them ever making any other sounds.

I do not believe it is the werewolf audio. It is probably the Alit audio -- due to their pleasant place in the alphabet, these sounds are also featured on Vivec and many other creatures.