For spatial sound authoring, two disciplines converge. An artist or content producer with strong emphasis on creativity brings the ideas or defines what should be done. Complementarily, skills from engineering are needed to implement the space and actually produce the effects. An user interface for artists should be intuitive and easily understandable. For the same reason in computer graphics different color models and naming schemes have been developed [Kaufman96]. For the sound designer, realism is not so important as the achieved impression. For example [Martens97], one might think about an virtual environment for flying starships, like that in movies and interactive games. Usually they produce sound even in outerspace sound waves do not travel through empty space. The user of a spatial sound authoring tool will create a soundscape with sound sinks, sound sources, and objects interacting with the sound waves. The sound objects have to be positioned and might be attached to geometrical objects. Their attributes need to be set. A development cycle comprising visualization, experiencing (i.e., listening with interaction), coverage checking, experimenting, evaluation and editing starts. Spatial attributes like the image breadth also known as localization blur [Blauert96, page 280], are important because they suggest the size of an object. In linear media (e.g., movies) this is not a big problem because sink (i.e., listener) positions are fixed. In interactive media the listener has total freedom to move around a sound objects (e.g., a piano that will be walked around cannot be well expressed by a point sound source).