Claim: The polyphonic singing of the Aka Pygmies was relisted on the UNESCO Cultural Heritage, in which the song can be subdivided into up to four parts described as an "ostinato with variations" similar to a passacaglia in that it is cyclical.
Evidence: The polyphonic singing of the Aka Pygmies was relisted on the Representative List of the Intangible Cultural Heritage of Humanity in 2008.