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Fig. 8.7 Initial scheme of the concert hall as a base of model 2. The rear wall of the stage and the rear wall of the audience area were divided into two. Sidewalls were divided into four
S4 values are shown in Fig. 8.11. To maximize S4, on the other hand, the rear wall of the stage and the rear wall of the audience area took on convex shapes. Thus it was proved that a “leaf-shape” plan of concert hall is one of the most optimal schemes, and this basic plan was applied in the design of the Kirishima International Concert Hall, which opened in 1994.
As for the conflicting requirements for S1 and S4, the maximization of S4 (IACC) may take a higher priority than S1 (listening level LL) because the preference increases with a decreasing IACC for all subjects tested (Singh et al., 1994), while there are a large individual differences in the preferred listening level LL (Sakai et al., 1997). Thus, listeners can choose the seat with respect to their preferred level LL when they buy tickets for concert (Section 8.3).
8.2.2 Two Actual Designs: Kirishima and Tsuyama
This preference-based optimization of architectural acoustics was applied to the design of the Kirishima International Concert Hall in cooperation with the architect Fumihiko Maki in 1992, as shown in Fig. 8.12 (Maki, 1997; Ando et al., 1997; Nakajima and Ando, 1997). Acoustic design elements were as follows (Ando, 1998,
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Fig. 8.8 Resulting shape for model 2 optimized with respect to scale preferences for listening
level, S1
Fig. 8.9 Contour lines of equal S1 listening level preference values calculated for the geometry shown in Fig. 8.8
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Fig. 8.10 Resulting of shape for model 2 optimized with respect to scale preferences for sound diffuseness and envelopment that are associated with minimal IACCs, i.e. S4
Fig. 8.11 Contour lines of equal S4 sound diffuseness preference values calculated for the geometry shown in Fig. 8.10
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Fig. 8.12 Scheme of the Kirishima International Concert Hall (Miyama Conceru) designed by architect Maki (1997). (a) Longitudinal section. (b) Plane of balcony level. (c) Plane of audience level
2007b): (1) A leaf-shape plan was applied, (2) the sidewalls were tilted, and (3) the ceiling consisted of triangular plates. These realized a small value of the IACC at nearly every seat (Photo 8.1).
Another example is the Tsuyama Music Cultural Hall (Suzumura et al., 2000) with a shape similar to that of the Kirishima Hall. An additional design, introduced 52 columns (each 30 cm diameter) as a design element in the hall
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Photo 8.1 Kirishima International Concert Hall (Miyama Conceru)
Photo 8.2 Tsuyama Music Cultural Hall with 52 columns each of 30 cm diameter around the walls
(Photo 8.2). The columns provide surfaces for scattering reflected sound waves for the higher-frequency range above 1 kHz. This avoids image shifts of sound sources on the stage, and brings about a smaller value of IACC for areas near the columns and at the seating-center area close to the stage. Because columns