 She was noticed internationally when she performed the alto part in Bach's "St Matthew Passion" in Vienna in 1955, conducted by Herbert von Karajan.She was identified with the part of Erda in Wagner's "Das Rheingold" and "Siegfried", sung first in 1959 at Covent Garden in London, and repeated at the Vienna State Opera and the Teatro Colón in Buenos Aires until 1975.She sang this role at the Bayreuth Festival 1960 to 1964 and 1967 to 1975, from 1964-1975 also the First Norn in "Götterdämmerung".