Why do people hear voices in the woods?

I've never known anyone to hear voices in the woods, but I believe there's a reason behind everything. I believe people hear voices in the woods for two reasons. One because either someone is there with them, or two, they are really crazy. I feel that way because if I was in the woods by myself and I heard voices, I would look around to see if I see anybody. If no ones there I would begin to question myself, like did I really hear that, or was it just in my head.