This work investigates the effects of diffusive surfaces on concert hall acoustics using scale models with regard to hall shape and diffuser location. Two simple 1:50 scale models (shoebox and fan-shaped) were produced to measure the RT and SPL, which were decreased by wall diffusers in both hall shapes. In the shoebox hall, SPL was increased especially in the frontal area but was decreased in the rear area due to redirection of the second reflections by the opposite lateral walls, whereas SPL was decreased in both the frontal and rear area in the fan-shaped hall. For in-depth investigation of diffuser location and profile, three shoebox model halls were reproduced: a 1:50 symphony hall, a 1:25 chamber hall and a 1:25 theater. Minimal reductions in RT and LL and decreased spatial deviation in acoustical parameters were established as criteria to determine the effective diffuser location. The halves of the lateral walls closest to the stage were found to be the most effective areas for diffuser installation. Additionally, large and sparse diffuser profiles usually provided better acoustical results.

Opera performance conveys both visual and auditory information to an audience, and so opera theaters should be evaluated in both domains. This study investigates the effect of static visual and auditory cues on seat preference in an opera theater. Acoustical parameters were measured and visibility was analyzed for nine seats. Subjective assessments for visual-only, auditory-only, and auditory-visual preferences for these seat positions were made through paired-comparison tests. In the cases of visual-only and auditory-only subjective evaluations, preference judgment tests on a rating scale were also employed. Visual stimuli were based on still photographs, and auditory stimuli were based on binaural impulse responses convolved with a solo tenor recording. For the visual-only experiment, preference is predicted well by measurements taken related to the angle of seats from the theater midline at the center of the stage, the size of the photographed stage view, the visual obstruction, and the distance from the stage. Sound pressure level was the dominant predictor of auditory preference in the auditory-only experiment. In the cross-modal experiments, both auditory and visual preferences were shown to contribute to overall impression, but auditory cues were more influential than the static visual cues. The results show that both a positive visual-only or a positive auditory-only evaluations positively contribute to the assessments of seat quality.

Although temples are important buildings in the Buddhist community, the acoustic quality has not been examined in detail. Buddhist monks change the location and direction according to the ceremony, and associated acoustical changes have not yet been examined scientifically. To discuss the desired acoustics of temples, it is necessary to know the acoustic characteristics appropriate for each phase of a ceremony. In this study, acoustic measurements were taken at various source locations and directions in Japanese temples. A directional loudspeaker was used as the source to provide vocal acoustic fields, and impulse responses were measured and analyzed. The speech transmission index was higher and the interaural cross-correlation coefficient was lower for the sound source directed toward the side wall than that directed toward the altar. This suggests that the change in direction improves speech intelligibility, and the asymmetric property of direct sound and complex reflections from the altar and side wall increases the apparent source width. The large and coupled-like structure of the altar of a Buddhist temple may have reinforced the reverberation components and the table in the altar, which is called the “syumidan,” may have decreased binaural coherence.