Quartal harmony
Chord building in fourths.
What it means
Quartal harmony designates the building of chords from stacked fourths instead of thirds. A sonority of D, G, C, and F, for instance, is a quartal chord. Because the third is absent, which in customary harmony determines the mode, such sonorities remain undecided between major and minor and seem open, floating, and austere.
Musical use
As a deliberate compositional principle, quartal harmony is a phenomenon of the twentieth century. It arose from the effort to detach from the third-stacked harmony of major-minor tonality without moving into complete chromaticism. Quartal sonorities have no unambiguous root, because in a stack of equal intervals no note stands out; they can therefore be freely shifted and connected.
It is especially widespread in modal jazz, where quartal voicings on the piano belong to the common sound image. There they replace the traditional third-chords, seem more modern, and leave the melody more room, because they do not fix the mode. In film music, too, quartal sonorities are often used for expanse and openness.
Historically, quartal stackings are not to be confused with the music of the Middle Ages, whose parallel fourths and fifths are a different matter: there two voices move in parallel, here chords are built.
Quartal harmony is to be distinguished from the suspension chord, which likewise contains a fourth in place of the third but rests on a triad and is traditionally resolved.
Quartal chords dispense with the third and thereby sound open and neither major nor minor. Early examples are found in Scriabin, Schoenberg, and Hindemith. In the modal jazz of the 1960s, quartal voicings on the piano became a hallmark of the style. A chord of three stacked perfect fourths seems floating and can easily be shifted in parallel.
Performance practice
Set quartal sonorities with even volume of all notes; any emphasis creates a root the sonority does not have. Watch the register, because in the low register quartal stackings quickly become muddy. And shift quartal chords in parallel — this is where their particular character lies.