POLYPHONIE X

'Polyphonie X' is a composition for eighteen instruments by Pierre Boulez written in 1950-51. It is in three movements. The piece is generally considered the nadir of Boulez's total serial period (the apex being Structures, book 1 of 1951–52). The title is often misinterpreted as having algebraic significance; in fact, the X is intended as a purely graphical symbol, implying the crossing of musical parameters which takes place in the score.
The work has only been performed twice, and only once in its entirety; reportedly Boulez was so disappointed when he heard a recording of the première that he immediately withdrew the work, intending eventually to subject it to a thoroughgoing revision. As of 2007 this has not happened, and the piece remains unpublished. Two recordings of ''Polyphonie X'' exist; one of the première by the Sinfonieorchester Baden-Baden conducted by Hans Rosbaud, another by the symphony orchestra of the RAI conducted by Bruno Maderna (first movement only).
The piece was written just before Boulez's other total serial works, the two ''Concrète Etudes'' and the piano duo, ''Structures I''.