There was no sound at first- just the echo of the large man's voice as it spilled down the gaping maw of blackness and away, through the facility. There was no strange mechanical voice, no synthesised garble. Just unending silence, only broken by the creak of metal and the groan of... 

The groan of something distinctly alive. The echoing nature of the facility made it impossible to tell where the sound had come from- it ricoched off of walls, floors and cielings, bounced about the group, and seemed to come from every which angle at once. It was followed by a shuffling noise, distant and faint, but audible, present... And coming closer.