Monumental orchestra composed of multiple configurations and shifting, city and its public spaces offer to the ears of their inhabitants a real urban symphony. Often overlooked as composers, these same individuals, daily users of urban public spaces, participate in the writing of the immediate and perpetual interpretation of this partition by performing their mundane activities. This project focuses specifically on some sounds which we define using the notion of "trace sonore". We consider the latter as the set of sounds that the user leaves in its wake through the actions of his own body by interacting in some way or another with the space. Thus, footstep sounds, guttural sounds, sounds due to contact of clothing, etc., become the object on which we focus.