 It is also one of only two times Max Lorenz (tenor) sang at Bayreuth after World War II, and his acting abilities lend the record further interest.During the 1960s, she had difficulties with her voice from singing such heavy parts for a decade, and returned to singing mezzo-soprano repertoire, such as Klytemnestra in "Elektra", the Nurse ("Die Frau ohne Schatten") and Waltraute.In 1968 she appeared as Ruth in a German-language production of Gilbert and Sullivan's "The Pirates of Penzance", and in 1970 she appeared in The Rise and Fall of the City of Mahagonny in Cologne.