Polychord

What it means

A polychord is a sonority consisting of two or more chords stacked on top of each other, for instance D major over C major. The chords remain audible as independent sonorities and yet blend into a common, richly colored whole. In chord symbols the polychord is usually written like a fraction: the upper chord above a horizontal line, the lower one beneath.

Musical use

Polychords occur above all in the music of the 20th century. Famous is the "Petrushka chord" in Igor Stravinsky's ballet Petrushka (1911), which sounds C major and F sharp major simultaneously. They are also common in jazz, where they appear as upper structures, in which one chord lies above a bass note or a basic chord.

The polychord should be distinguished from the slash chord, in which only a single bass note is changed (for instance C/E), and from polytonality, which means several keys at once, whereas the polychord stays at the level of chords.

Performance practice

When you play a polychord, listen to both chords individually and to their interplay. On the piano you can play the lower chord in the left hand and the upper one in the right and then balance the volumes so that both remain recognisable.