You had to stay in your squeaky pew last night, at the performance of the same 40 part motet by actual live human beings, the singers of the Schola Cantorum and of the Pacific Collegium, at SS Peter and Paul church in North Beach. And you would have spooked them quite a bit if you were to approach your ear to focus on one voice in particular. Yet, as different as the experience of the music was, it was as enjoyable: the same whirlwind of sounds dancing around you, near or fear, coming and going, surprising you here and disappearing there. The 8 groups of 5 voices encircled the audience in the aisles of the church, with the conductor standing in the middle, making very large caricatural gestures to be seen by all.