Composer Ludwig van Beethoven discovered the totality of his deafness when he saw birds flying out of the bell tower as a result of the bells' tolling but could not hear the bells. St. Stephen's Cathedral has 23 bells in total. The largest is officially named for St. Mary, but usually called "Pummerin" ("Boomer") and hangs in the north tower. At , it is the largest in Austria and the second largest swinging bell in Europe after the "Peter" in Cologne Cathedral).