Polytonality is the use of two or more different keys in a composition at the same time. For instance, a chord consisting of the notes C, E, F#, G, A#, and C# would be polytonal, as C, E, and G form a C major chord while F#, A# and C# form an F# major chord. Russian composer Igor Stravinsky was a notable exponent of polytonality, using it in works like The Rite of Spring and Petrushka; other composers who utilized this technique include the Americans Charles Ives and Aaron Copland, the Frenchman Darius Milhaud, and the Englishman Benjamin Britten.
Unknown and Forgotten Composers 