She began studying singing at the age of 15 at the Zurich Conservatory , and made her operatic debut in the title role of Puccini 's Madama Butterfly at Solothurn-Biel Municipal Theater in 1940 .
Her first performance in opera was singing Madame Butterfly in Puccini 's Madama Butterfly at Solothurn-Biel Municipal Theater in 1940 .