Numerical characterization of acoustic scattering coefficients of one-dimensional periodic surfaces

In room acoustics design, one-dimensional periodic surfaces, such as ribbed or corrugated walls, are ordinary used to scatter reflected sound and to increase sound field diffuseness. There exists some measured data of random-incidence scattering coefficient for periodic surfaces, however a substantial database is not yet provided. Instead of the measurement, numerical analysis in a free field is useful to calculate directional scattering coefficients. This paper numerically investigates the characteristics of random- and normal-incidence scattering coefficients of one-dimensional periodic surfaces, focusing on the effects of shape, height and width of surface profile. Additionally, 1/4-scale model measurements are conducted for typical profiles in order to verify the numerical results. Finally, optimal height-to-period ratios, maximizing random- or normal-incidence scattering coefficient, are found for sinusoidal, triangular and rectangular profiles, respectively.