As we went along the guide would explain to us how the various things worked.  He also talked about how loud things were in there while mining was going on.  He turned on one of the machines, and even without it actually drilling in the rock it was so loud it was hard to hear yourself think.  And that was just with one machine.  He said at any given time there might be 4 or 5 of them running, and they were much louder while drilling in the rockface.