poliharmónia
Poliharmónia refers to the simultaneous sounding of more than two distinct pitches, a concept explored and expanded upon in music theory and composition. It goes beyond simple consonance or dissonance, involving the intentional juxtaposition of multiple harmonic structures or tonal centers within a single musical passage. Composers may achieve poliharmónia through various techniques, such as layering independent melodic lines, each with its own harmonic implications, or by superimposing chords derived from different keys.
The term is often associated with early 20th-century musical developments, where composers sought to break away