Prior to the invention of modern software, concert-hall design was about theories and cardboard models, about estimating and trial and error. Although some older halls were revered for their sound, more were “knocked down because they had bad acoustics,” according to world-renowned acoustician Yasuhisa Toyota.
New technologies have revolutionized every aspect of design culture, from architecture and mechanical engineering to the relatively new field of acoustic engineering and design. Such fantastical concert halls as Casa da Música in Portugal and Auditorio de Tenerife in Spain seem to have appeared from a dream, but their designs serve the music even more than the imagination.
Paul Scarbrough, a principal with Norwalk, Connecticut’s Akustiks, has been serving the music as an acoustical designer for more than 30 years. Most recently, Scarbrough, in conjunction with HGA Architects, designed the acoustics for the Concert Hall at the Ordway Center for the Performing Arts in Saint Paul, Minnesota. His initial challenge at the Ordway was working with not one, but four resident companies that call the Ordway Center home.
“We start every project with a very intensive set of discussions,” Scarbrough says. “In this case, we met all four of the Arts Partners: the Saint Paul Chamber Orchestra (SPCO), the Schubert Club, the Minnesota Opera, and the Ordway Center itself. We initially began [renovating] the music theater that was already part of the music center. But after a study, it was determined that wouldn’t meet the needs of all partners.”
From the Ordway’s opening on Jan. 1, 1985, the respective resident companies battled for performance space. Those disagreements were eventually solved under The Arts Partnership, which laid the foundation for the spirit of collaboration that allowed the Concert Hall to emerge as a solution.
“Thankfully, the tug of war that had ensued among the resident companies was resolved before we were on board,” Scarbrough says. “The Concert Hall moved the lion’s share of the activity of one partner to a new space. So now, the music theater could expand its schedule for the remaining partners.”
As with all good designers, Scarbrough prompted a series of discussions to understand the partners’ goals for the new Concert Hall—one of the most telling came from asking the SPCO about the character of the acoustics it wanted to create.
“The most important word to come out of those discussions was ‘intimacy,’” Scarbrough says. “There was a great desire by the SPCO to create a concert space where you feel connected to the performers and the performers feel really connected to the audience.”
Once the design goals were established, Scarbrough used some complex acoustical-engineering software to accomplish them. “In the design process, we use computer-modeling tools like CATT-Acoustic, which allows you to make a 3D model of the proposed concert space and calculate a series of acoustic parameters about its performance,” he says. “You can also build a 1:10 or 1:20 scale model of a space and actually test it with real sound. Each modeling technique tells you something different about the performance of the space.”
Scarbrough also uses Trane Acoustics Program (TAP) to model HVAC systems and prevent those systems’ sounds from becoming a distraction during performances. And using SoundPLAN, Scarbrough modeled noise in the outside environment to determine whether the Ordway would impact the surrounding neighborhood or if neighborhood noise would impact the Ordway.
“SoundPLAN allows you to create a landscape, describe the topography of a site, and put in all the buildings and all the noise sources to understand how those sources act in the environment,” Scarbrough says. “It actually produces a 3D image with color coding showing the noise levels all around your site.”
Materials used at the Ordway included Formglas GFRG (PDF) for the walls, which provided additional stiffness and rigidity. The hall’s beautiful accordion ceiling was developed with HGA’s CEO, Tim Carl.
“We needed the acoustic boundary of the room to be quite tall,” Scarbrough says. “But if that was expressed, the room would feel uncomfortable and work against the sense of intimacy. Tim came up with a screen made out of 5/8-inch wooden dowels. It’s sound-transparent, and the dowels are on spacing that varies subtly as it goes along the curve. That variation between the spacing of the dowels ensured there wouldn’t be any negative effects from all the spaces and dowels being the same size.”
When collaborating with HGA, Scarbrough made design exchanges through Autodesk AutoCAD. “We use the architect’s CAD drawings and increasingly Revit to calculate the cubic volume of the space and the surface areas of materials, which are important things we need to understand in order to calculate certain key acoustic parameters like reverberation time,” he says. “That is a function of the cubic volume of the space and the acoustic properties of the materials in the space.”
To get just the right timing of sonic reflections—in order to create a rich, clear sound—Scarbrough focused on every detail of the hall, including seating. Akustiks specified solid wood for the bottoms and backs of the seats and even the maximum thickness of the seat padding.
But even with all those mathematical equations and material considerations, there was still plenty of art to complement the science. “Tim and I worked hand in glove from the very beginning of the process to opening day,” Scarbrough says. “Tim is a wonderfully sensitive architect. We put out acoustic criteria, which his team developed and refined and which is reflected in the architecture. We worked back and forth until we came to a resolution that reflected our acoustic aims but was also a beautiful piece of architecture.”
In the end, the final evaluation of what makes a successful concert hall is more intuitive than scientific. “It’s by listening,” Scarbrough says. “Sure, there are measurements we can take and software to characterize what’s happening acoustically in a space, but the final judgment is the human ear. How does the ear respond? Do listeners feel engaged with the music and a part of the music? Do the performers feel comfortable on the stage and confident that their sound is reaching everybody? Those are the final things, and though they’re subjective, that’s what it’s all about.”