Page 22 - Spring 2009

WHAT IS SO SPECIAL ABOUT SHOEBOX HALLS? ENVELOPMENT, ENVELOPMENT, ENVELOPMENT
Marshall Long
Marshall Long Acoustics 13636 Riverside Drive Sherman Oaks, California 91423
In spite of many attempts to surpass
the sound quality obtained from
shoebox shaped concert halls, this
traditional design continues to lead the
pack in sound quality ratings. In Leo
Beranek’s careful surveys of concert halls
and opera houses (1962, 1996, and 2004), four of the five high- est ranked halls in the world have a rectangular shape. A deep- er understanding of what differentiates them from surround halls, fan shaped halls, or many other configurations will enable designers and architects to achieve a higher level of acoustical excellence in modern concert halls.
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.
“The prominent feature
of the most successful halls is their rectangular shape.”
Fig. 1. Grosser Musikvereinssaal, Vienna, Austria (Beranek, 1996).
Technical factors in hall design
Studies by Ando (1985) and Beranek (1996, 2004) have identified quantitative factors that contribute to hall quality. In approximate order of importance, these are: (1) listener envel-
opment, that is, the sense of being surrounded by sound, in particular, in the time period greater than 80 milliseconds after the arrival of the first sound; (2) reverberant character, usually quantified in terms of the reverberation time; (3) dif- fusion, an important factor contributing to envelopment; (4) sound strength, as determined by taking measurements at various seats throughout the hall of sound delivered from a
Fig. 2. Symphony Hall, Boston, Massachusetts, United States of America (Beranek, 1996).
Shoebox Halls 21