heterophony
noun
het·er·oph·o·ny ˌhe-tə-ˈrä-fə-nē 
plural heterophonies
: independent variation on a single melody by two or more voices
Example Sentences
Recent Examples on the Web The same motifs are often played simultaneously at different speeds — a technique called heterophony — which subtly reinforces the dramatic narrative. 
BostonGlobe.com, 24 Oct. 2021 His 1920s recordings with the Red Hot Peppers reached the peak of the New Orleans style of group embellishment and collective improvisation, with its trademark heterophony and polyphony. John Edward Hasse, WSJ, 7 Sep. 2018
BostonGlobe.com, 24 Oct. 2021 His 1920s recordings with the Red Hot Peppers reached the peak of the New Orleans style of group embellishment and collective improvisation, with its trademark heterophony and polyphony. John Edward Hasse, WSJ, 7 Sep. 2018 Word History
Etymology
Greek heterophōnia diversity of note, from heter- + -phōnia -phony
First Known Use
1919, in the meaning defined above