Improvement of stage acoustics in a small circular-shaped recital hall

This paper investigates how stage acoustics can be improved by the installation of on-stage reflectors in a small recital hall with a circular floor plan. The target hall, which is designed as a second floor with a seating capacity of 533, has an average reverberation time of 1.31 seconds in the mid-frequency band at the audience seats when empty, and an average side reflection sound ratio of 0.4. The target hall, assessed as having a circular planar shape with wide left and right sides compared to its depth, is not conducive to performers. Therefore, we measured the stage acoustics according to ISO 3382-1, with a grid spacing of 1 m above the stage. We created a simulation model based on the measurement results. To enhance the stage acoustics, a movable reflector was placed on the stage, and the effective area of the stage surrounded by the reflector was varied and compared through simulation. The results indicated that as the effective area of the stage surrounded by the reflector decreased, STEarly improved. Meanwhile, in the audience, the installation of stage reflectors showed no significant difference in reverberation time or clarity, but the sound pressure level was slightly improved.