The Second Vatican Council impacted the use of liturgical music within religious communities. Two U.S. Trappist monasteries, New Melleray Abbey in Dubuque, Iowa, and Gethsemani Abbey in Bardstown, Kentucky, evidenced distinctive approaches to the musical freedom resulting from the Vatican II reforms. New Melleray incorporated contemporary folk music and instruments. At Gethsemani, Father Chrysogonus Waddell pioneered the use of Gregorian notation and English psalmody. The musical changes had a profound effect on the Trappists’ celebration of the Mass and the praying of the Liturgy of the Hours.
Eden, B.L. "The sounds of Vatican II: musical change and experimentation in two U.S. Trappist monasteries, 1965-1984." U.S. Catholic Historian, v. 32, no. 4 (Fall 2014), pp. 77-97.