Quartal Harmony and sus ChordsQuartal chords can have a variety of uses. Sometimes they imply quartal harmonyand other times they are merely used to create interesting voicings of tertian chords; bothare staples of modern jazz keyboard harmony. There are many Preludes with isolatedchords voiced in fourths or with a right-hand figuration using fourths, and even thesequick references, along with Kapustin’s other devices, create a modern jazz context forhis musical ideas. Most of the examples discussed below feature more extensive use ofquartal techniques, and most use tertian harmony with quartal chord voicings

Modern Jazz Theory