But these speeches are only a part of the soundscape. The production is suffused with music"all of it a cappella vocalizing by the cast. We hear barracks songs, patriotic songs, hymns and drinking songs"and, of course, Christmas carols. Erick Lichte and Timothy C. Takach's arrangements are exceptionally rich and intricate. The singer-actors weave a choral spell that is not soon forgotten. One could try to single out …