A parametric description describing the wideness of a non-point sound source is generated and linked with the audio signal of said sound source. A presentation of said non-point sound source by multiple decorrelated point sound sources at different positions is defined. Different diffuseness algorithms are applied for ensuring a decorrelation of the respective outputs. According to a further embodiment primitive shapes of several distributed uncorellated sound sources are defined, e.g. a box, a sphere and a cylinder. The width of a sound source can also be defined by an opening-angle relative to the listener. Furthermore, the primitive shapes can be combined to do more complex shapes.