It's something I've always meant to ask. The reason I ask is that I watch the old Pancreas and Pride vids and I notice how loud the hits and slams are. When Fedor was reigning body shots against Big Nog the first time you could really hear them (which made Stephen Quadros say "it sounds like someone hitting a buffalo with a baseball bat").
I know that in pro-wrestling the rings are mic'd and calibrated and maybe they used that same approach towards their MMA rings. Maybe it was because the Japanese crowd was so quiet that you could hear everything. I don't know. The sounds are noticeably louder in Japanese rings.
The ref had a mic over his ear under the "ref cam" helmet , it looks like a stylus. Both EliteXC and Strikeforce have used this in the past, and yes, it is awesome.
I think the difference might be that the crowd in japan is so quiet during an MMA match that you can hear every strike. I was blown away the first time I watched a DREAM event live via stream and I could hear the fighters breathing.