A trope or tropus may be a variety of different things in medieval and modern music.
The term trope derives from the Greek τρόπος (tropos), "a turn, a change" (Liddell and Scott 1889), related to the root of the verb τρέπειν (trepein), "to turn, to direct, to alter, to change" (Merriam-Webster Online Dictionary). The Latinised form of the word is tropus.
In music, a trope is adding an additional section, or trope to a plainchant or section of plainchant, thus making it appropriate to a particular occasion or festival.
In Medieval music
From the 9th century onward, trope refers to additions of new music to pre-existing chants in use in the Western Christian Church (Planchart 2001).
Three types of addition are found in music manuscripts: (1) new melismas without text (mostly unlabelled or called "trope" in manuscripts) (2) addition of a new text to a pre-existing melisma (more often called prosula, prosa, verba or versus') (3) new verse or verses, consisting of both text and music (mostly called trope, but also laudes or versus in manuscripts) (Planchart 2001). The new verses can appear preceding or following the original material, or in between phrases.
In the Medieval era, troping was an important compositional technique where local composers could add their own voice to the body of liturgical music. These added ideas are valuable tools to examine compositional trends in the Middle Ages, and help modern scholars determine the point of origin of the pieces, as they typically mention regional historical figures (St. Saturnin of Toulouse, for example would appear in tropes composed in Southern France). Musical collections of tropes are called tropers.
In 20th-century music
In certain types of atonal and serial music, a trope is an unordered collection of different pitches, most often of cardinality six (now usually called an unordered hexachord, of which there are two complementary ones in twelve-tone equal temperament). Tropes in this sense were devised and named by Josef Matthias Hauer in connection with his own twelve-tone technique, developed simultaneously with but overshadowed by Arnold Schoenberg's (Sengstschmid 1980).
Hauer discovered the 44 tropes, pairs of complementary hexachords, in 1921 allowing him to classify any of the 479,001,600 twelve-tone melodies into one of forty-four types and this may have assisted in Hauer's music becoming entirely twelve-tone by the 1920s (Whittall 2008, 24).
- Trope (cantillation), or trop ((Yiddish טראָפ), the notation for accentuation and musical reading of the Bible in Jewish religious liturgy
- Liddell, Henry George, and Robert Scott. 1889. "τρόπος]". In An Intermediate Greek-English Lexicon. Oxford. Clarendon Press. Online at Perseus. (Accessed 22 December 2009)
- "trope", Merriam-Webster Online Dictionary, 2009, http://www.merriam-webster.com/dictionary/trope, retrieved 2009-10-16
- Planchart, Alejandro Enrique. 2001. "Trope (i)". The New Grove Dictionary of Music and Musicians, ed. S. Sadie and J. Tyrrell. London: Macmillan.
- Sengstschmid, Johann. 1980. Zwischen Trope und Zwölftonspiel: J.M. Hauers Zwölftontechnik in ausgewählten Beispielen. Forschungsbeiträge zur Musikwissenschaft 28. Regensburg: G. Bosse. ISBN 3-7649-2219-2
- Whittall, Arnold. 2008. The Cambridge Introduction to Serialism. Cambridge Introductions to Music. New York: Cambridge University Press. ISBN 978-0-521-86341-4 (hardback) ISBN 978-0-521-68200-8 (pbk).
- Hansen, Finn Egeland. 1990. "Tropering: Et kompositionsprincip". In Festskrift Søren Sørensen: 1920 . 29. September. 1990, edited by Finn Egeland Hansen, Steen Pade, Christian Thodberg, and Arthur Ilfeldt, 185–205. Copenhagen: Fog. ISBN 87-87099-32-2
- Knapp, Janet. 1990. "Which Came First, the Chicken or the Egg?: Some Reflections on the Relationship between Conductus and Trope". In Essays in Musicology: A Tribute to Alvin Johnson, edited by Lewis Lockwood and Edward Roesner. [Philadelphia?]: American Musicological Society. ISBN 1-878528-00-9
- Summers, William John. 2007. "To Trope or Not to Trope?: or, How Was That English Gloria Performed?" In Music in Medieval Europe: Studies in Honour of Bryan Gillingham, edited by Terence Bailey and Alma Santosuosso. Aldershot, England; Burlington, VT: Ashgate Publishers. ISBN 0-7546-5239-4 ISBN 978-0-7546-5239-7