It has been nearly a decade since the beloved Italian mezzo-soprano Cecilia Bartoli last sang in New York. David Letterman, Jon Stewart and others have been known to grow beards when they’ve left the city’s limelight. But the whiskers Ms. Bartoli was sporting recently weren’t quite of that variety.

She had instead taken on some startlingly convincing facial hair to sing the title role in Handel’s “Ariodante,” a male character originally sung by a castrato. In an interview in her dressing room here, Ms. Bartoli said that while she likes to fully inhabit her roles, she was initially unsure about the more-than-stubble.