The aim of this project is increasing the research carried out by Sylvain Marchand, researcher of the LaBRI (Laboratoire Bordelais de Recherche en Informatique), about the RetroSpat System. RetroSpat stands for "Retroactive Spatializer" and it is a free software project for the spatialization of sounds represented in the spectral domain. This system is intended to be a spatializer with perceptive feedback. More precisely, RetroSpat can guess positions of physical sound sources (e.g. loudspeakers) from binaural inputs, and can then output multichannel signals to the loudspeakers while controlling the spatial location of virtual sound sources. So, the project will be based practically on improving the localization method as a result of the localization corresponding to a sound source, changing the software architecture to merge the localization and spatialization parts and on an improvement of the graphical user interface. This project is organized as follows. In the first section is presented some history of acousmatic music. Next a description of the model in Section 2 is done including the spatialization and localization methods. Section 3 is dedicated to the Source code. The problems with the actual software and its possible reasons of appearance are discussed in Section 4. Finally there are some conclusions of the work done.