Task: Question Answering
Input (English): Passage: In 1955, Paul Hindemith revised the work to achieve more clarity. According to Wolfgang Rathert, Hindemith "sought to moderate Reger's 'uncontrolled invention'", while Kirshnit described Reger's original scoring as "gloriously polychromatic". Hindemith "thinned" the orchestra, especially the horns. In Reger's scoring, the organ reinforced the voices throughout the piece, resulting in a lack of clarity for the polyphonic passages. Hindemith used the organ only for climaxes. In the double fugue, he assigned one theme to a voice, but the other simultaneous theme to the orchestra. Hindemith's approach, which enables more analytical listening, seems justified by Reger's own scoring of later compositions which were more refined and focused. It is probably due to his version that Der 100. Psalm enjoyed continuous presence in concert halls, while other works by Reger were neglected.François Callebout wrote an organ version that was published in 2004 by Dr. J. Butz. Gabriel Dessauer explains in the preface that Reger's work was conceived for oratorio choirs of up to 500 singers at the beginning of the 20th century. The organ version enables smaller choirs to perform the music. This version was premiered in 2003 by the Reger-Chor in St. Bonifatius, Wiesbaden, the parish to which the composer belonged during his studies in Wiesbaden. The organ was played by Ignace Michiels, organist at the St. Salvator Cathedral in Bruges.Hanns-Friedrich Kaiser, KMD (director of church music) in Weiden, where Reger grew up, wrote a version for choir and organ, which he conducted at the opening of the festival Reger-Tage at the church St. Michael on 16 September 2012, with organist Michael Schöch. 
Question: What is the last name of the person who assigned one theme to a voice, and a simultaneous theme to the orchestra in the double fugue?
Output (English): Reger.