Best Sounding Listening Rooms are… ‘Shoebox’ Shaped!
WHAT IS SO SPECIAL ABOUT SHOEBOX HALLS?
ENVELOPMENT, ENVELOPMENT, ENVELOPMENT
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 highest ranked halls in the world have a rectangular shape. A deeper 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.
Based on surveys of musicians, conductors, and knowledgeable 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.
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 envelopment, 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) diffusion, 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 fixed source on the orchestra platform; (5) clarity, the strength of the initial sound along with early reflections arriving soon thereafter; and (6) warmth, the strength of the bass. Additional contributing factors that are not usually considered in these ratings include audience comfort, a low level of background noise, clear sightlines, and convenience. The absence of any of these qualities can offset the other positive factors.