Braun's main areas of research were German and British music history of the 17th and 18th centuries, especially North and Central German church music, opera and Singspiel, art song and music theory of this period. His important research work includes Britannia abundans, a fundamental study of Anglo-German musical relations at the time of William Shakespeare, The change of style of music around 1600, an analysis of the transition from Renaissance music to Baroque music, and Thöne und Melodeyen, Arien und Canzonetten, a comprehensive treatise on the German art song in the Baroque era. Within the Neue Handbuch der Musikwissenschaft edited by Carl Dahlhaus and Hermann Danuser, Braun wrote the volume on 17th century music, and in the edited collectionGeschichte der Musiktheorie he is author of the volume on the historical development of German music theory from Sethus Calvisius to Johann Mattheson. Braun wrote 15 monographs, about 140 scientific essays and 38 articles for the new edition of the encyclopedia Die Musik in Geschichte und Gegenwart. In addition, he published eight editions of sheet music by German composers of the 17th and 18th centuries. From 1987 to 1993 he was founder and director of the publication series Saarbrücker Studien zur Musikwissenschaft, Neue Folge. On his 65th and 75th birthday, one commemorative publication each was dedicated to him. Braun was a member of the Scientific Advisory Board of the Critical Complete Edition of all works of Johann Rosenmüller. Braun died in Saarbrücken on Webarchiv
Work
Die mitteldeutsche Choralpassion im 18. Jahrhundert. Evangelische Verlags-Anstalt, Berlin 1960
Das Problem der Epochengliederung in der Musik. Darmstadt 1977,
Britannia abundans. Deutsch-englische Musikbeziehungen zur Shakespearezeit. Schneider, Tutzing 1977,
Die Musik des 17. Jahrhunderts. Laaber-Verlag, Laaber 1981,
Samuel Michael und die Instrumentalmusik um 1630. Wissenschaftliche Buchgesellschaft, Darmstadt 1990,
Die Musiktheorie des 16. und 17. Jahrhunderts in Deutschland, volume 2: Deutsche Musiktheorie von Calvisius bis Mattheson. Wissenschaftliche Buchgesellschaft, Darmstadt 1994,
Thöne und Melodeyen, Arien und Canzonetten. Zur Musik des deutschen Barockliedes. Niemeyer, Tübingen 2004,
Editions
Heinrich Schütz: Unser Herr Jesus Christus in der Nacht, da er verraten ward. Bärenreiter, Kassel 1961
Johann Walter: Sämtliche Werke, volume 4. Bärenreiter, Kassel 1973
Johann Gottfried Müthel: Klavierkonzerte. Katzbichler, Munich 1979