A cappella It's amazing how effectively these six world-famous opera overtures translate for a cappella voices in this delightful medley! Sung entirely on the syllables da ba da, bop bop bop and doo be dop, this fast-paced musical collage is guaranteed to entertain and educate! It features snippets from: Fidelio, The Barber of Seville; Die Fledermaus; The Magic Flute; The Marriage of Figaro and William Tell.