Evaluation of diffuse reflections in a 1:10 scale model

Abstract

The acoustical properties of a multipurpose hall (opera mode) were measured in a 1:10 scale model to investigate the effect of diffuse reflections. Measurements were made in stall areas with and without diffusers on the walls adjacent to the pit and on the side walls. The diffusers consisted of 15- to 25-cm-high hemispheres and 25-cm high polygons. A mix of these diffusers was used to cover about 40% of the area of the side walls. It was found that 1-IACCE3 increased at positions close to the walls adjacent to the pit and the first reflection with maximum amplitude increased in some seats. The possibility of diffuse reflections either hitting the proscenium wall or soffit close to the side wall first, as well as reflections coming from both sides of the hall explains the reason for the bunch of early reflections in the impulse responses. The effect of diffusers at each receiver position was investigated via subjective evaluation. The results from the subjective evaluation indicated that diffuse reflections were preferred to specular reflections.