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WHAT IS SO SPECIAL ABOUT SHOEBOX HALLS? ENVELOPMENT, ENVELOPMENT, ENVELOPMENT Marshall Long Marshall Long Acoustics 13636 Riverside Drive Sherman Oaks, California 91423 n spite of many attempts to surpass “The prominent feature Technical factors in hall design I the sound quality obtained from shoebox shaped concert halls, this traditional design continues to lead the Studies by Ando (1985) and of the most successful halls is Beranek (1996, 2004) have identified quantitative factors that contribute to pack in sound quality ratings. In Leo their rectangular shape.” hall quality. In approximate order of Beranek’s careful surveys of concert halls importance, these are: (1) listener envel- and opera houses (1962, 1996, and 2004), four of the five high- opment, that is, the sense of being surrounded by sound, in est ranked halls in the world have a rectangular shape. A deep- particular, in the time period greater than 80 milliseconds er understanding of what differentiates them from surround after the arrival of the first sound; (2) reverberant character, halls, fan shaped halls, or many other configurations will usually quantified in terms of the reverberation time; (3) dif- enable designers and architects to achieve a higher level of fusion, an important factor contributing to envelopment; (4) acoustical excellence in modern concert halls. sound strength, as determined by taking measurements at various seats throughout the hall of sound delivered from a Highly-rated halls Based on surveys of musicians, conductors, and knowl- edgeable listeners Beranek (1996, 2004) ranks the five best halls as: Grosser Musikvereinssaal (Vienna), Symphony Hall (Boston), Teatro Colon (Buenos Aires), Konzerthaus (Berlin), and Concertgebouw (Amsterdam). Figures 1-5 from Long (2006) show sketches of these halls based on Beranek’s work. Most were constructed in the late nineteenth and early twentieth centuries. Konzerthaus was originally built in 1821 and rebuilt in 1993 after having been destroyed in World War II. While there are other fine halls, most have similar features. In fact four of the next five top rated halls are also rectangular. Fig. 2. Symphony Hall, Boston, Massachusetts, United States of America (Beranek, Fig. 1. Grosser Musikvereinssaal, Vienna, Austria (Beranek, 1996). 1996). Shoebox Halls 21 side walls in rectangular halls provide early reflections that increase clarity, along with later side reflections that sur- round or envelop the listener. The latter reflections include not only the first reflected sound but also additional multiple reflections extending out in time. The best halls also have flat or gently sloping floors and elevated orchestra platforms. Most platforms are at or above the level of the last row of seats. This is in contrast to a legit- imate theater where the seating is raked for better sightlines. A typical stage height in a legitimate theater in the United States is 42 inches, based on the average seated eye height of about 44 inches. In Vereinssaal the orchestra platform is 39 inches, however, the main floor is flat except in the rear

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