I think it just means louder that most (but not all) of the other people. I didn't think much of it until I had some American friends visit me and I took them to bar near where I live. I didn't really noticed anything while we were all sitting together.
When I crossed the room to go to the bar for another round, then I noticed that I could clearly hear my American friends voices above everyone one else in the room. I could clearly hear their conversation from across the bar. They were just speaking somewhat louder than everyone else.
Over here seems like every friend group has the dumb one. When they nice person who cares?