Development of scattering surfaces for concert halls

The degree of diffusion, characterized by the “scattering coefficient” of surface materials, has been known to be one of the most important factors in determining the acoustical qualities of concert halls. Based on the suggested ISO method, which measures the random-incidence scattering coefficient of surfaces in a diffuse field, the scattering coefficients of different sizes and densities of wooden hemispheres and cubes were measured in model-scale reverberation rooms. The results show that hemispheres with a height of more than 15 cm have the highest average (500 Hz to 4 kHz) scattering coefficient. It was also found that the scattering coefficient becomes higher when the diffuser density reaches about 50% for hemispheres and 30% for cubes.