Shirley Verrett was an American operatic mezzo-soprano who successfully transitioned into soprano roles making her a Soprano sfogato. Verrett enjoyed great fame from the late 1960s through the 1990s; she was particularly well known for singing the works of Verdi and Donizetti.

Anna Fitziu was an American soprano who had a prolific international opera career during the early part of the 20th century. Her signature roles included Fiora in L'amore dei tre re, Mimi in La bohème, Nedda in Pagliacci, and the title roles in Isabeau, Madama Butterfly, and Tosca. After her singing career ended, she embarked on a second career as a voice teacher. Among her notable pupils was opera singer Shirley Verrett.