The most important factors governing the acoustical success of a concert hall are size and shape. Size, which is related to both seating capacity and volume, is of paramount importance. Great concert halls contain 2000 seats or less. The most significant exception to that seating capacity is Boston Symphony Hall, with 2625 seats; however, if it were redesigned to adhere to modern standards of fire safety and comfort, Boston might have only 1840 seats within its existing internal dimensions. In today’s world, concert hall committees who ask their design team for a 2500- or 3000-seat hall with great acoustics are asking the impossible, because the space will be too large for great acoustics.
Historically, the tried-and-true shape for an acoustically superior concert hall has been the “shoebox.” The nickname alludes to the basic shape of a narrow rectangle with parallel walls, high ceilings, and one or two shallow side balconies.
Interior of Carnegie Hall, New York, NY
Courtesy Carnegie Hall
A less successful shape that was very popular in the middle years of the last century is the ‘fan-shape’ or ‘wedge-shaped’ hall, whose side walls fan out from the stage. The use of a steel structural frame, rather than a traditional timber and masonry construction, permitted long spans, deep balcony overhangs, and the use of lightweight materials for walls and ceilings. These apparent advances allowed architects to depart from the rectangular form of the traditional concert hall. The new structural designs were validated by scientific calculation of stresses and strains. Reverberation time, a concept initially explored by Wallace Clement Sabine, the acoustical designer of Boston Symphony Hall, was endorsed as the overriding acoustical parameter. Indeed, there were no other objective acoustical criteria.
Interior of Louise Davies Hall, San Francisco, CA
Curiously, the next generation abandoned Sabine’s favored shoebox shape, perhaps because he could not support his preference with scientific data. The influential Bauhaus movement had left architecture with a rationalist approach: form follows function. Theater consultants could explain how sightlines worked. Before 1980, acousticians could not explain how or why acoustics in a narrow rectangular space worked. Thus, architects opted for sightlines over sound considerations. They built concert halls that fanned out from the stage, thereby increasing seating capacity and providing front-facing sight lines and shorter viewing distances for audience members than the traditional shoebox. Fan-shaped halls were the design of choice from about 1910 on, particularly in North America, where more new construction was taking place than in Europe and the rest of the world. That trend gave us such albatrosses as Toronto’s Roy Thompson Hall (seating capacity 2812), San Francisco’s Louise Davies Hall (capacity 2,743), Dallas’ Fair Park Music Hall (capacity 3,420), and Houston’s Jesse Jones Hall (capacity 3000). Only gradually, after too many of these oversize, fan-shaped halls had been built, were acousticians able to identify the scientific reasons that these spaces are dreadful for music.
Exterior of Fair Park Music Hall, Dallas, Texas
Photo by Gil R. Glover, courtesy Dallas View
The advantage to fan-shaped spaces is that they afford excellent sightlines to a large number of persons who are seated relatively close to the stage. There is an economic corollary. Because of the relatively high seat count, such halls can generate high box office receipts, which represent earned income for the presenting organization.
The disadvantage to fan-shaped halls is acoustical. Fan-shaped halls permit few lateral reflections, which means that the presence, envelopment and warmth characteristic of good acoustical sound are lacking. Fan-shaped halls frequently suffer from a ‘bounce-back’ effect off the rear wall, which can be disconcerting to audience members in some seats, and can be disastrous for musicians on stage whose ability to hear one another is seriously compromised.
Even with renovations, a fan-shaped performance space will remain inadequate because its fundamental shape precludes adequate lateral sound. This is the primary reason that most renovations are essentially doomed to be patch jobs. If the size and shape are wrong to begin with, there is relatively little that can be done to remedy acoustics, even in the most beloved architectural landmark.
The most remarkable step forward in concert hall design in the past quarter century was Dallas’ Morton H. Meyerson Symphony Center, which opened in 1989. The Dallas concert hall committee was determined to have the best concert hall in the world. They opted for a single-purpose hall, specifically designed for symphonic music. They also gave equal authority to architect and acoustician. Those decisions led to a revolutionary design for Meyerson.
Artec Consultants, the hall’s acoustical team, began with the basic parameters they knew to be advantageous. Artec’s Nicholas Edwards built upon ideas of Russell Johnson, the firm’s founder, combining them with his own research and those of the German group in Göttingen. Systematically working through each area of the hall on each level, he generated sketches that indicated the best placement for walls in order to optimize the all-important lateral reflections. As his ideas crystallized, he began calling the evolving room shape the ‘reverse fan.’ This was the eventual shape of both the Dallas concert hall and its younger sibling, Symphony Hall in Birmingham, England. Both these halls have strong ‘shoebox’ shaping, with the ‘reverse fan’ at the back of the room.
Edwards designed Meyerson in 1981, sketching with pencil on paper, using string and pins to track sound reflections. By the time he and his colleagues at Artec refined the design for Symphony Hall in Birmingham, the design concept was computer-aided. Computers allowed them to track the behavior of sound within a given space in three dimensions.
According to Edwards, the first ‘lateral’ halls, including those in Kitchener, Ontario, and Colorado Springs, achieved lateral sound with first-order reflectors directing the sound into the audience areas. This approach has a pronounced effect on the architecture of the space. Meyerson directs sound using second-order reflections from side walls and horizontal soffits, as occurs in a traditional shoebox concert hall. In Birmingham, the directing of sound is achieved by bouncing sound sometimes three or more times from the walls and/or soffits. These higher effects could only be studied once Edwards had written appropriate software and the computers were available to assist with the design task.
Another factor that affects concert hall acoustics is materials. This category includes not only what is on the walls, floors, ceilings, and soffits, but also the upholstery and fixtures. Obviously, these particulars differ with each individual hall, which is another reason that halls have such distinct personalities, aesthetically as well as acoustically.
The rake of audience seating affects sound reflection. A shallow rake permits sound to reflect not only between the side walls, but also from front to back, thereby enveloping the audience in sound. A good concert hall wants the seating rake shallow, even flat, to allow the sound to reflect multiple times off the walls and ceiling, creating additional reverberation. Its audible results are presence, warmth, resonance, envelopment—the qualities we associate with rich sound.
From Out of Place: A HyperHistory of the Elusive Acoustics of Concert Hall Venues
By Laurie Shulman
© 2002 NewMusicBox