Page 25 - Spring 2009

Fig. 5. Concertgebouw, Amsterdam, Netherlands (Beranek, 1996).
the sound strength in the rectangular rooms by about 6 dB compared to the surround halls.
Non-rectangular halls
There are other room shapes used in concert hall design. The most common is the surround hall where the audience seating surrounds the orchestra. This style has been used in Berlin Philharmonic Hall, Suntory Hall in Tokyo, and Disney Hall in Los Angeles. Figure 6 shows a sketch of Berlin Philharmonic Hall. Non-rectangular halls can be designed with the goal of achieving the same technical factors as those present in shoebox halls. In the areas of reverberation and clarity, surround halls can achieve results comparable to those found in rectangular halls. Hidaka et al. (2008) recent- ly published a detailed comparison of measured data in these two types of halls. Surround halls are not as successful as rec- tangular halls in achieving envelopment, source strength, and minimizing seat to seat variation. This is particularly evident with directional instruments such as the French horn, trum- pet, and piano (with its reflecting board sending the high fre- quency sounds forward), as well as a soprano voice. In these factors the Hidaka et al. (2008) study shows clear differences.
Shoebox halls
Some acousticians and architects are still building halls in the shoebox style. Sala São Paulo in Brazil is a good recent example. The late Russ Johnson, acoustician for Sala São Paulo, told me he thought it might be his best hall. Seiji Ozawa Hall in Lenox, Massachusetts is another fine example.
It is encouraging that the testimonial evidence is supported by the technical studies. It seems clear that the inclusion of a reflective band above the first floor seating helps maintain lateral reflections and envelopment. This combination of a raised orchestra platform and low rake angle for the seating is a common feature in the world’s best halls. In the balconies reflective bands are also present in rectangular rooms and are augmented by overhangs from the upper balconies and ceil- ings above. If acoustical excellence is of prime importance and shoebox halls sound best, we should be building more of them.AT
References
Ando, Yoichi (1985). Concert Hall Acoustics (Springer-Verlag, New York, 1985).
Beranek, Leo L. (1962). Music, Acoustics & Architecture (John Wiley & Sons, New York,
1962).
Beranek, Leo L. (1996). Concert and Opera Halls How They Sound
(Acoustical Society of America, Melville, NY, 1996).
Beranek, Leo L. (2004). Concert Halls and Opera Houses: Music,
Acoustics, and Architecture (Springer-Verlag, New York, 2004). Hidaka, Takayuki, Beranek, Leo L., and Nishihara, Noriko (2008). “A comparison between shoebox and non-shoebox halls based on objective measurements in actual halls,” J. Acoust. Soc. Am.
123, 2973 (A).
Long, Marshall (2006). Architectural Acoustics (Elsevier, Burlington,
24 Acoustics Today, April 2009
MA, 2006).