New device for measuring mapping of sound scattering coefficients of vertical uneven surfaces in a reverberant workplace

The interior wall facings that delimit industrial rooms are often uneven, i.e. they often have relief, and that causes the sound propagating in such premises to be acoustically scattered. Acoustic prediction software making it possible to plot maps of the sound field in workplaces needs characteristics such as the sound absorption or the sound scattering coefficient of such surfaces. In this work, we propose to obtain experimental this sound scattering coefficient of vertical surfaces in situ thanks to a new measurement. The experimental technique that was originally developed under free-field conditions was adapted to attenuate the echoes coming from reverberation and the noise coming from sources and machines present on the site. For that purpose, a first device has been developed containing a multipolar acoustic array and an impulsive source used respectively for achieving spatial filtering and for separating in time the different echoes. The new device developed and presented in this paper has been used on several measurement campaigns, and it has thus been possible to study, among other things, the reproducibility of the results. Installing a large multipolar array made it possible to obtain good accuracy for the results at low frequencies. The scattering coefficient of a vertical surface containing a rectangular cavity was measured for various angles of incidence in a noisy and reverberant environment. Finally, those measurements made it possible to map the sound scattering coefficient in the XY directions and thus to highlight the highly variable scattering mechanisms of a uneven structure depending on the measurement point.