Missa Pange lingua

Polyphonic chant is a sacred vocal tradition in which two or more independent voices sing liturgical material at the same time, creating vertical harmony from originally monophonic chant. Emerging from the practice of adding a second voice to chant (organum), it favors perfect consonances (fourths, fifths, and octaves) and often places a sustained chant line (tenor) beneath more florid upper parts. In its classic medieval Western form, it is unaccompanied (a cappella), modal rather than tonal, and frequently governed by rhythmic modes. While the Notre Dame school in Paris codified much of its technique, related polyphonic chant practices also exist in other liturgical cultures (e.g., Georgian and Corsican traditions), each with distinctive sonorities and voice-leading norms.