Tenor Stephen Gould, who announced earlier this month that he had been diagnosed with incurable bile duct cancer, has died. Gould's agent Stephanie Ammann confirmed the singer died Tuesday in Virginia. The singer withdrew this summer from the Bayreuth Festival in Germany, where he was scheduled to perform the title roles in “Tannhäuser” and “Tristan und Isolde” and Siegfried in “Götterdämmerung.”