Validation and limitations of a device for measuring the sound scattering coefficient of walls facings present in workshop.

The relief of wall facings present in workshops induces the scattered propagating waves. Predictive acoustic software for mapping the acoustic pressure field at workplace uses the acoustic characteristics such as absorption or diffusion of these wall facings. A system for determining the in situ scattering sound coefficient of walls was developed. The measurement technique developed originally in free field conditions has been adapted to overcome problems of parasite echoes coming from reverberation of the other inner-walls of the building and from noisy sources present on the site. For this, a multipolar acoustic array and an impulsive source respectively for performing spatial filtering and separating false echoes are used. Measurements have been carried out to validate this device on panels with a known scattered acoustic behaviour (Schroeder diffusers) and on facings containing rectangular cavities for several incidence angles and at various distances. These measures allowed to establish the validity range and limitations of this device.