Francis Poulenc's "Dialogue of the Carmelites," one of the Met's most acclaimed productions, airs live today starting at 12 noon. Poulenc tells the story of Carmelite nuns martyred in the French Revolution with what the New York Times calls "eloquent music that hardly calls attention to itself yet lingers with you." Patricia Racette, Erin Morley, Isabel Leonard, and Felicity Palmer head the cast; Louis Langree conducts.