Acoustical remodeling of a large fan-type auditorium to enhance sound strength and spatial responsiveness for symphonic music

The Grand Theater in the Sejong Performing Arts Center in Seoul, Korea is a proscenium hall with 3022 seats. Originally built in 1978, the Grand Theater was remodeled in 2004 to provide variable reverberation time (RT) using a sound system. Recently, a second remodeling was scheduled to enhance the hall’s acoustic quality, especially its RT, sound strength (G) and binaural quality index (BQI = 1-IACCE3), based on architectural acoustic analysis. In the remodeling plan, the wall covering and chair materials were changed to produce longer RT and higher G. For the remodeling design, side balconies were added to the first and third floors to provide lateral reflections to the audience area. The orchestra shell and various ceiling/wall reflectors were planned to provide more early reflections to the audience area. To verify the design, the effects of these structures on the sound pressure levels and spatial parameters of early sound in the audience area were investigated by open-type 1:10 scale model measurement. In addition, the acoustical qualities of the remodeled hall were evaluated using computer simulations and 1:50 scale model measurement. The results show that G was improved by 5 dB and BQI by 0.24, whereas the occupied RT at mid-frequencies became variable from 1.47 to 2.24 s.