Trichord

Contiguous trichords in C major.

In music theory, a trichord is a group of three different pitch classes found within a larger group (Friedmann 1990, 42). For example a contiguous three-note set from a musical scale (Houlahan & Tacka 2008, 54) or a twelve-tone row. The term is derived by analogy from the 20th-century use of the word "tetrachord". Unlike the tetrachord and hexachord, there is no traditional standard scale arrangement of three notes, nor is the trichord necessarily thought of as a harmonic entity (Rushton 2001).

Just as a diatonic scale is conventionally said to be constructed of two disjunct tetrachords (CDEF+GABC=CDEFGABC), a pentatonic scale can be constructed of two disjunct trichords (ACD+EGA=ACDEGA; GAC+DEG=GACDEG).^{[citation needed]}

Milton Babbitt's serial theory of combinatoriality makes much of the properties of three-note, four-note, and six-note segments of a twelve-tone row, which he calls, respectively, trichords, tetrachords, and hexachords, extending the traditional sense of the terms and retaining their implication of contiguity (Babbitt 2003, 59).

Allen Forte occasionally makes informal use of the term trichord (Forte 1973, 124 and 126) to mean what he usually calls "sets of three elements" (Forte 1973, 3, 23, 27, and 47), and other theorists (notably including Hanson 1960, and Gamer 1967, 37, 46, 50–52), mean by the term triad, a three-note pitch collection which is not necessarily a contiguous segment of a scale or a tone row and not necessarily (in twentieth-century music) tertian or diatonic either.^{[citation needed]}

See also

• Triad
• All-trichord hexachord
• Viennese trichord

References

• Babbitt, Milton (2003). "Twelve-Tone Invariants as Compositional Determinants (1960)". In The Collected Essays of Milton Babbitt, edited by Stephen Peles, Stephen Dembski, Andrew Mead, Joseph Straus, 55–69. Princeton: Princeton University Press.
• Forte, Allen (1973). The Structure of Atonal Music. New Haven and London: Yale University Press. ISBN 0-300-01610-7 (cloth) ISBN 0-300-02120-8 (pbk).
• Friedmann, Michael L. (1990). Ear Training for Twentieth-Century Music, p.42. ISBN 9780300045376.
• Gamer, Carleton (1967). "Some Combinational Resources of Equal-Tempered Systems". Journal of Music Theory 11, no. 1 (Spring): 32-59.
• Hanson, Howard (1960). Harmonic Materials of Modern Music: Resources of the Tempered Scale. New York: Appleton-Century-Crofts.
• Houlahan, Mícheál, and Philip Tacka (2008). Kodály Today: A Cognitive Approach to Elementary Music Education. Oxford and New York: Oxford University Press. ISBN 9780195314090.
• Rushton, Julien (2001). "Trichord". The New Grove Dictionary of Music and Musicians, second edition, edited by Stanley Sadie and John Tyrrell. London: Macmillan Publishers.

Further reading

• Gilbert, Steven E. (1970). "The Trichord: An Analytic Outlook for Twentieth-Century Music". Ph.D. diss. New Haven: Yale University.

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