

In their own words: "The Voca people are 8 friendly aliens from the planet Voca, a musical planet that has no verbal communication but use vocal expressions only. They have heard the music from earth for decades now and with their imitation abilities they have decided to pay a one evening tribute to humanity and to perform the songs they love as musical- gratitude."
Frankly, I think they're stretching it a bit about the planet Voca (who's heard of that place?), but their performances do pay wonderful homage to great music that everyone recognizes here on planet Earth.
Actually based in Israel, The Voca People group consists of five men and three women with amazing voices. They use those voices in a phenomanal a cappella method, creating not just music but vocals that imitate the sounds of drums and other musical instruments, creating an awesome blended sound in a humorous and entertaining way. In other words, they put on a great show for their very appreciative audiences.
(source: http://www.squidoo.com/vocapeople)