Subjective and objective evaluations of a scattered sound field in a scale model opera house

Scattered sound fields in an opera house were objectively and subjectively evaluated through acoustical measurements in a 1:10 scale model and through auditory preference tests. Acoustical characteristics were measured in the stalls area with and without diffusers, both on the sidewalls close to the proscenium and in the soffit of the side balcony. Installed diffusers reduced the initial time delay gap and amplitude of the first reflected sound, and decreased sound pressure level (SPL), reverberation time (RT), and early decay time (EDT) at most seats due to the increased scattering and absorption. After diffuser installation, C(80) and 1-IACC(E3) increased at the front seats and decreased at the rear seats. Subjective evaluations showed that the preference of scattered sound fields correlates highly with loudness and reverberance. It was also found that EDT and SPL are dominant parameters describing subjective preference for scattered sounds in this experimental condition.