polytonality
/ˌpɑliˌtoʊˈnæləti/
noun
- The use of two or more different keys or tonal centers at the same time in a piece of music.
- Many 20th-century composers experimented with polytonality to create tension and dissonance.
- In jazz, polytonality can be heard when different instruments play in different keys simultaneously.
- The composer's use of polytonality gave the symphony a complex, layered sound.