Diffuser design for both auditorium and stage acoustics in concert halls

Abstract

This study investigates the effect of the shapes and the locations of diffusers on acoustical characteristics, both in the audience area and on the stage, using a 1:50 scale model. Random-incidence scattering coefficients of the diffusers were measured in a reverberation chamber according to ISO 17497-1. One of the halls investigated was rectangular shape with 2,600 seats based on the Boston Symphony Hall. Impulse responses were recorded for measurement of RT, EDT, C80, G, Ts, and ST1 in the model hall. In addition, a method to provide the number and amplitude of reflection rays were proposed to quantify diffusion effect. The results show that an appropriate design of diffusers in halls affects the sound field of both the auditorium and the stage of the hall. It was also found that the effective number of surface reflections at a receiver position actually quantifies the sound diffusion. Through instillation of omni-directional diffusers close to stage walls, the number of reflected rays increases not only in the audience area but also in the stage area.