Ahrens received his education in Benedictine abbeys and at the Staatliche Akademie für Kirchen - und Schulmusik in Berlin. He was professor of improvisation and organ at the Berlin Institute, lecturer at the Berlin Akademie and professor of church music at the Berlin Hochschule für Musik. He has served as an administrator and professor at many institutions and received several distinguished awards for his efforts. The bulk of his compositions consist of organ and some choral works.