In Modules 11 and 13 we studied three-note chords called triadsand used them to harmonize melodies, a
defining feature of Western music called “tertian harmony,” or harmonies built on the interval of the third. In
addition to triads, composers have harmonized melodies using “tertian” chords made of four notes, and even
five or more notes.
The four-note chord is called the seventh chord,named for the interval of the seventh created between the
lowest and highest notes of the chord. Subsequent chords with more notes are named from the interval number
between their root and highest notes.
371
SEVENTH CHORDS
Originally, composers used sevenths as added notes to a melody and its harmony—they were non-chord tones that created
dissonances (intervals that required a resolution). By the eighteenth century, sevenths became an accepted part of a composer’s
harmonic vocabulary; eventually, they were used extensively by some composers (such as Claude Debussy) and in jazz and some
popular music.
Historical note: Seventh chords
Triad Seventh
chord
Ninth
chord
Eleventh
chord
7 9 11
372 Qualities of Seventh Chords
373 Dominant Seventh Chords
374 Two Methods of Writing Dominant Seventh Chords
376 Harmonizing Music in Major Keys Using Triads or Dominant
Seventh Chords in Root Position
377 Inversions of Dominant Seventh Chords
377 Figured Bass Symbols for Seventh Chords
379 Harmonizing Music in Major Keys Using Inverted
Dominant Seventh Chords
379 Chord Progressions Using Dominant Seventh
Chords in Major Keys
381 Dominant Seventh Chords in Minor Keys
383 Workbook