Wall diffuser designs for acoustical renovation of small performing spaces

This paper investigates the material characteristics of diffusers for acoustical renovation of existing small performing spaces. Consideration is given to acoustical effects on sound fields through the practical cases of two performing halls: the Chamber Hall (450 seats) and the M-Theater (630 seats) in the Sejong Performing Arts Center, Seoul. The Chamber Hall was completely refurbished into a recital hall from its previous shape of a rectangular conference space. The saw-tooth shaped wall diffuser profile in the Chamber Hall was designed using glass-fiber reinforced concrete for mid-frequency sound diffusion. The M-Theater was renovated as a live and intimate space for dramatic performances with a design that included more seats on the upper floors and additional spaces above ceiling reflectors. The vertically-patterned diffuser profile with protruded cubic surfaces in the M-Theater was designed using glass-fiber reinforced gypsum for sound diffusion in the major speech frequency range. Designed diffuser profiles were evaluated for both halls by measurements of scattering and diffusion coefficients of the 1:10 scale model diffusers. The effects of diffusers in both halls were also investigated by covering the lateral walls close to the stages with reflective materials to control diffusive surfaces. As a result, spatial uniformity increased with diffusive wall profiles in both halls.