“unnecessery by-produkt (of the reciving listerner at autonomus composition prodcedure)”:
In Xenakis’ list of the fundamental phases of a musical work, as taken from Formalized Music: Thought and Mathematics in Music, the listener is not even mentioned. The final phase of a musical work, according to Xenakis, is its sonic realization.(Xenakis, 1971, 22)
Xenakis, I. (1971). Formalized Music : Thought and Mathematics in Music. Number 6 in Harmonologia series. Indiana University Press, Bloomington. Revised edition.

http://en.wikipedia.org/wiki/Iannis_Xenakis

http://www.medieval.org/music/modern/xenakis.html