I am not pertaining to any specific group but those singing acapella are really what you call born and trained singers. They really have the discipline to stay on their designate voice level, and that is not an easy thing. Most of the time when we sing we tend to follow who had the dominant voice. It takes a lot of continues practice and hardwork to make an Acapella good to hear. You just don't shout to your hearts desire. Most group singers voice tend to be good and pleasing when musical instrument are accompanied but with acapella your really true voice comes out. Most likely it is easy to identify who got wrong or trip out from his designated voice.
I tried acapella singing during my college days, I have the chance to sing in a graduation ceremony. That is how I begun loving acapella, and here I met my date.
