Robert Siegel talks to Michael Oehler, a music management professor at University of Cologne in Germany, about his study on why people get so irritated by the sound of fingernails on a chalkboard. Oehler led a team of researchers from the University of Cologne and the University of Vienna in a study designed to pinpoint the source of this and similarly irritating sounds. Scientists found that the most obnoxious elements of the noises may be amplified by the shape of the human ear.