Noted: At the University of Wisconsin at Madison, where European musicians had flocked in the years before World War II, Mr. Hoiby studied with the renowned Danish pianist Gunnar Johansen. He also encountered atonal music for the first time, reacting with revulsion. ?If music doesn?t have melody and harmony and rhythm as I understand it,? he said, ?I?m not interested. A lot of that stuff sounds like wallpaper to me.?