I think it's pretty easy to explain, really. I've actually had it happen to me while speaking. You notice that you don't have eye contact with the crowd anymore, they're all watching to see what the ill person will do, so it's natural to turn around and see what the problem is.

A couple years ago my daughter sang at a big event at the KY Center for the Arts. There was this kid in the back row of the choir who was getting sick to her stomach. EVERYONE in that place knew it, she was causing such a distraction. They finally got her off the risers and...about...halfway off the stage before she called Earl ALL OVER THE PLACE.