A baroque orchestra occupied center stage between vacant chairs and a vacant podium. Richardson Auditorium buzzed with the tuning of instruments, the chatter of the audience, and the anticipation of the Glee Club’s annual Walter L. Nollner concert. This concert, named after the late Glee conductor from 1958 to 1993, has also become a celebration of the ensemble’s graduating seniors. As the clock hit 7:30 p.m., the choir filed in from the wings, filling the rows of empty chairs. Then, Gabriel Crouch, Princeton’s Director of Choral Activities, stepped onto the podium and raised his baton.