ccato peaks to the B and C above.??? Sack did sing in opera (she created the role of Isotta in Richard Strauss's Die Schweigsame Frauin 1935 and sang??? Zerbinetta (Ariadne auf Naxos) for Beecham at Covent Garden), but she acheived her greatest success as a concert singer.??? Her personality and technique were better suited the light music of such composers as Johann Strauss and Arditi.??? Sack's