Abstract. In this talk we present an overview of needs and some advancements in sound and music analysis, synthesis and processing based on special representations. Representations are often inspired by the physics of sound production, by perception and/or by new and old mathematical ideas. Successful methods are usually the ones that have an intuitive connection with features in sound signals, while being well grounded in a solid mathematical framework. Our tour starts with adapted time-frequency and time-scale representations, it touches physical modeling and audio effects, it travels through spatial audio and sound source separation. The flavor of the talk is informal, with a focus on ideas and working examples rather than theory.