Robert Sholl teaches at the Royal Academy of Music and at the University of West London. He has published on a wide range of twentieth-century music. He was editor of Messiaen Studies, and has recently written on Arvo Part, Stravinsky's Le Sacre du Printemps, Messiaen and Berio. As an organist Robert has given recitals at St Paul's Cathedral, Westminster Abbey, Notre-Dame-de Paris, and at the Madeleine, and he will perform all of Messiaen's organ music in 2016-17. Sander van Maas is Assistant Professor of Musicology at the University of Amsterdam, previously Endowed Full Professor of Dutch Contemporary Composed Music at Utrecht University, and held visiting positions at Boston University, Harvard and the London College of Music. He is author of The Reinvention of Religious Music: Olivier Messiaen's Breakthrough toward the Beyond and editor of Thresholds of Listening: Sound, Technics, and Space.