From 1983 to 1994 he was director of the musicological institute of the University of Cologne.
From 1975 to 1983 he was director of the musicological seminar of the Westfälische Wilhelms-Universität in Münster.
Was chairman of the Joseph Haydn Institute in Cologne and the Robert Schumann Research Centre in Düsseldorf as well as president of the Gesellschaft für Musikforschung.
Studied musicology at the University of Cologne from 1950 to 1955.
From 1976 until his death he was a full member of the North Rhine-Westphalian Academy of Sciences, Humanities and the Arts. His focus is on medieval music theory, and on the music history of the 19th and 20th centuries.
In 1969 he was appointed professor at the University of Cologne.
Received his doctorate with a dissertation on Nicolaus Wollick and in 1964 his habilitation with Untersuchungen zu Musikpflege und Musikunterricht in den deutschen Lateinschulen vom ausgehenden Middle Ages bis um 1600.