In this Dec. 24, 2012 photo provided by the Metropolitan Opera, Elza van den Heever, center right, sings the role of Elisabetta with Joyce DiDonato, center left, in the title role during a dress ... more 

In this Dec. 24, 2012 photo provided by the Metropolitan Opera, Elza van den Heever, center right, sings the role of Elisabetta with Joyce DiDonato, center left, in the title role during a dress rehearsal of Donizetti's "Maria Stuarda," at the Metropolitan Opera in New York. (AP Photo/Metropolitan Opera, Ken Howard) less