in music, the simultaneous use of different tonalities or keys. Bitonality—the use of two different tonalities —is the most common type of polytonality.
In practice, two monotonal lines with independent functional systems and cadences are rarely combined. As a rule, polytonality means the simultaneous use only of the chords of different tonalities. The classic example, the “Petrushka chord” in Stravinsky’s ballet Petrushka, combines the tonic of C major and that of F sharp major. Like other chords of this type, the Petrushka chord is strongly dissonant and dramatic. It is used as the “leading harmony” with which Petrushka is identified. Polytonality, one of the elements of the contemporary modal-harmonic system, has been widely used by D. Milhaud, B. Bartok, and other 20th-century composers.
IU. N. KHOLOPOV