In this text, the author argues that space should be considered as important a musical parameter in acousmatic music composition as more conventional musical parameters in instrumental music. There are aspects of sound spatialisation that can be considered exclusive to the acousmatic language: for example, immersive spatialisation places listeners in an environment where they are surrounded by speakers. The author traces a history of immersive spatialisation techniques, and describes the tools available today and the research needed to develop this parameter in the future. The author presents his own cycle of works within which he has developed a new way to compose for a spatial parameter. He calls this technique timbre spatialisation.