Notwithstanding her great success in the German repertory, Régine Crespin was quintessentially a French artist. With an unmistakable sensuality betraying her origins in Mediterranean France, she was guided by an unfailing sense of elegance. Whether as Kundry, the Marschallin, Carmen, Didon, Amelia in Un ballo in maschera, or Sieglinde, her large, lush voice was deployed with refined abandon. Her top register, powerful and soaring when it was working as the singer wished, sometimes emerged congested, as tones that began as clarion would cloud over and lose their cutting edge. A...