Ec(h)osystem is a transmedia deployment produced in collaboration with Nathan Prost and Marie Rossi, investigating the possibility of hyperbolising the third place of use of an art school. What minimal device would enable a discussion between the activating bodies and the space through the mediation of the latter's physical parameters (vibration, luminosity)? The sound device - operating a continuous recording - acts as a non-linear supra-echo by orchestrating a spatial and temporal redistribution of sound. It uses its own cognition to select from all the sounds heard those that it reproduces and those that it ignores. By playing continuously, it becomes a constant and irregular echo, with its own memory and way of expressing itself. This sound echo triggers a luminous reaction. A light panel changes according to what the sound device produces. It takes into account its own parameters, sensitive properties that it transforms into other sensitive properties. The panel varies in luminous intensity, enabling it to express a changing relationship with all the material objects in the space, accentuating cast shadows or obstructing the space entirely. In this way, light reveals its potential for spatial interaction. The device's global cognition is activated by solenoid effectors attached to the metal surfaces of the staircase handrail. In the event of sound saturation, a purge-reset system is put in place, physically activating the architecture, emptying the sound memory but at the same time replenishing it with the sound of the space. The meticulousness of the space becomes a global sound feedback loop. The installation does not claim to be an autonomous device orchestrating its own relationship to the world. It amplifies relationships that are already present, but whose possibilities for interaction are cross-fertilised by the device. The device emanates from the site and does not go beyond it, but reinvents it through its new technical possibilities.