The invention concerns a process for joint synthesis and spatialization of multiple sound sources in associated spatial positions, including: a) a step of assigning to each source at least one parameter (pi) representing an amplitude; b) a step of spatialization consisting in implementing an encoding into a plurality of channels, wherein each amplitude (pi) is duplicated to be multiplied to a specialization gain (gim), each spatialization gain being determined for one encoding channel (pgm) and for a source to be spatialized (Si); c) a step of grouping (R) the parameters multiplied by the gains (Pim), in respective channels (pg1, . . . , pgM), by applying a sum of said multiplied parameters (pim) on all the sources (Si) for each channel (pgm), and d) a step of parametric synthesis (SYNTH(I), . . . , SYNTH(M)) applied to each of the channels (pgm).