poème rec. > music tracks rec. Published versions were not suitable for our reconstruction because of subsequent editing. We found the original production tapes at the Institute of Sonology of The Hague: three mono tapes, one stereo tape, and one three-channel 35-mm perfo tape (the master). We digitized the four pre-master tapes, then synchronized using the perfo master tape and the Columbia version (authorized by Varèse) as references. Check the high correlation between the sonographic analysis of the final seconds of the Poème and one original sketch. Also see Concret PH.