He began his teaching career in 1947 and received his PhD in 1951. His dissertation, The Rhythm of Twelfth-Century Polyphony: its Theory and Practice outlines his ideas on modal interpretation of organum duplum.
His doctoral work, "The Rhythm of Twelfth-Century Polyphony: Its Theory and Practice," explored his ideas about the modal interpretation of organum duplum, which he developed during his teaching career that began in 1947.