Singing even one high C can be an event for the tenor and his audience. Everyone in the room knows how easily it could go wrong. Multiply that pressure by nine? You get “Ah, mes amis.” Gaetano Donizetti wrote this high-stakes aria for his opera La Fille du Régiment. The young hero Tonio has just enlisted in the army and received permission to marry the girl of his dreams. “Ah, mes amis” is his celebration: Tonio’s bursting with so much joy that the guy sings nine – count ‘em, NINE – high C’s. In this episode, host Rhiannon Giddens considers the sheer athleticism it takes to pull off “Ah, mes amis” with a singer, a vocal coach and a former NFL player. And once they’ve surveyed this Mount Everest of tenor arias, you’ll hear tenor Javier Camarena scale its heights from his base camp on the Metropolitan Opera stage.