In this paper, we present ListenSpace, a graphical authoring tool especially designed for audio-augmented reality in the context of LISTEN, a European project (IST program). LISTEN is devoted to the design, development and experimentation of interactive soundscapes created for augmenting an everyday environment. This new type of multi-sensory content requires the design of a specific authoring tool allowing describing, controlling and testing the soundscape. The paper compares different approaches for describing virtual sound scenes according to the specific context and describes how the authoring tool has been designed to fulfil this goal.