I was kneeling down and working the drill slowly into the wall at the time. I had my ear plugs in, my safety glasses on, and was lost in my own thoughts. Suddenly, over the squeal of the drill wearing down the rock, I heard a strange noise. It was loud. I could hear it over the noise of the drill, even though I had the ear plugs in. At first I thought it was just the drill bit doing its job on the cave. It would frequently complain by screeching and whining as we forced it into the wall. But this was different. It took me several full seconds to comprehend that this was coming from inside the hole, and not the bit. I stopped drilling and yanked my earplugs out just in time to hear the most terrible scream I have ever heard trail off and echo into the darkness of the cavern. I stared wide-eyed at the hole. For several moments I didn't move, nor did I breathe. I turned to look at B. Moments earlier he had been lying on the rope bag catching a nap. Now, he was standing upright, mouth open, with a look of concern on his face! I turned and looked into the hole again, half expecting to see a demon face staring back at me.