Among the questions regularly put to me, those that recur most often touch upon three aspects, three things to consider that are, truth to tell, unending within the domain of organised sounds. Those questions that take the lead are usually concerned with space – the representation of space as well as the production of space. Then come those that deal with listening, active or passive. Last are those relating to tools for making and for listening. Together, these approaches run through the stages that are very natural in position problematics: where, when, how, for whom, why? I would like, in formulating these repeated questions once more, to make myself re-orientate them in such a way to show that by bringing to bear forty years of experience, I have tried to reply to them as much through practice as through theory, putting forward the idea of a family of operational concepts linked together through the perceptual radical ‘acous’: acousmatic, acousmonium, acousmographe, acousmathèque.