Definition
Polytonality is the simultaneous use of two or more keys in different layers of the music (melody in one key, accompaniment in another). With two keys it is called bitonality. It differs from the polychord (an instantaneous sonority) because each layer has its own tonal coherence over time: melodies, cadences, scales.
Historical examples
- Charles Ives: Variations on “America” for organ (with bitonal interludes added later) and many pieces with bands playing in different keys.
- Igor Stravinsky, Petrushka (1911): C major and F# major superimposed (the Petrushka chord); The Rite of Spring (1913): Fb major + Eb7 in the “Augurs of Spring.”
- Darius Milhaud: Saudades do Brasil (1920), dances in which the melody and the accompaniment are in different keys; Milhaud theorized and practiced polytonality systematically.
- Béla Bartók: in Mikrokosmos several teaching pieces put the two hands in different keys or modes.
- Benjamin Britten, Sergei Prokofiev, Aaron Copland: more occasional uses.
How it is perceived
The ear tends to fuse the layers into a single complex harmony, unless they are separated by:
- register (at least an octave),
- timbre (instruments of different families),
- rhythm (layers with distinct rhythmic figures),
- dynamics and space (panning, reverb depth).
The more separated the layers are, the more you hear a “double tonality”; the more fused they are, the more you hear an extended chord.
Choosing the keys
| Relationship between the keys | Example | Effect |
|---|---|---|
| Tritone | C + F# | maximum contrast, grotesque (Petrushka) |
| Semitone | C + Db | harsh, unsettling |
| Major second | C + D | Lydian, bright (C + D = extended C Lydian) |
| Minor third | C + Eb | blues, ambiguous major/minor |
| Major third | C + E | augmented, dreamy |
| Fifth | C + G | almost tonal, “open” (pandiatonicism) |
Polytonality in jazz and pop
- Jazz upper structures and polychords produce a brief polytonal effect.
- Outside playing: the improviser plays for a few bars in a key a half step above (side-slipping): temporary bitonality.
- In pop it is extremely rare in the strict sense; more common are riffs or samples in one key with harmonies that “reread” them.
Practical example (controlled bitonality)
- Bass layer: ostinato in C major (C – G – A – E in quarter notes, double basses and piano left hand).
- Upper layer: melody in D major (with F# and C#) on flutes and violins.
The whole sounds like C Lydian with a “fairy-tale” color: it is the kind of bitonality used in many animation soundtracks.
Producer exercise
- Track 1 (Rhodes, register C2–C3): loop in A minor Am – G – F – E.
- Track 2 (synth lead, above C5): melody in Eb minor pentatonic.
- Separate them with EQ and panning (Rhodes −20 L, lead +20 R), different reverb (room on the Rhodes, hall on the lead).
- Use the bitonality for 4 bars as a “moment of madness” and then bring the lead back to the Rhodes’ key.
Related topics
Hybrid chords and polychords, pandiatonicism, upper structure triads, Schoenberg (introduction), harmony for film.