The Dial-O-Map 25° sound installation, which is structured around two major perspectives, entirely transforms the acoustic and visual environment of the nave. The first perspective offers the visitor coming into the museum on the ground floor, a peripheral approach to the work without being able to enter the heart of it. In this entirely empty zone we can only hear the murmur of the mechanism.
The second perspective depends on the overall layout of the warehouse. On the first floor the gangway that goes around the nave at a height of 5m, traces an important zone for discovering the installation and offers a panoramic listening space. At this level of the building, the installation becomes completely visible; it is composed of a louver, a collection of reflectors, sound equipment and several groups of spotlights.

Occupying most of the exhibition space, the Dial-O-map 25° obstructs the overall panorama of the nave with a vast white belt of 800m² made out of PVC. This cone-shaped pavilion stands above a self-supporting metallic structure. It is inclined at 25° and forms a louver that directs the waves high up towards the roof of the building. The structural option of this module relies on an interplay of acoustic symmetries with the slope of the roof 14 m above it. The angle is critical for generating a resurgent sound effect. In the centre of the nave the load-bearing foundations of the building form a series of semi-circular arches at the bottom of which there are 3 white modules which disseminate the sound. Each one is composed of a pair of concave acoustic reflectors designed to direct the high-pitched frequencies towards the gangways. The design of these reflectors relies on a simple curvilinear abscissa calculation and on tests to shape flat surfaces. They are disposed back to back and equipped with pairs of satelite speakers fixed 2m above the ground on brackets. Between each pair of reflectors, a low frequency box with a huge spout on top of it is oriented towards the ridgepole of the building. 36 HMI-Horiziode spotlights (cold light) shower light on the whole installation.

The sound diffusion is managed from the internet network by transferring audio-files. Secondly the data is controlled at a distance and managed through a spatialisation interface that spreads the sound throughout the nave. While the sound is being diffused, the role of the building is to act as an enveloping texture which can itself reconstruct all of the sound values, the dynamics and the duration of propagation of the sound. It fixes the effects of the propagation and condensation of the successive layers of sound for the listener for the last time. These links rely on the interplay between vertical and horizontal lines of force which are important in the nave.

The structural rules of The Dial-O-Map 25° are directly linked to the principal of the occupation of the space and to the role of the spectator listening while moving around in this context. Before being a stable volume for the sedimentation of the sound, the nave produces a phenomenon of friction on the sound textures and their rhythmic articulations. Travelling through the installation, the listener links the different fragments and creates listening segments which are in perpetual mouvement.