Sound Principles

Gregory M. Donley Magazine Staff

Floor plan

Marcel Breuer’s 1970 addition to the Cleveland Museum of Art included the only auditorium the Hungarian-born modernist architect ever built. With about 750 seats, Gartner Auditorium was conceived as a multi-use hall that would not only provide a fitting home for the McMyler Organ, but would also accommodate concerts as well as events such as scholarly lectures that required electronic amplification. In keeping with the building’s overall aesthetic, the visual quality of the space was austere, with the building exterior’s horizontal granite stripes finding a perpendicular analogue in a regular pattern of vertical wooden ribs running floor-to-ceiling and over every surface of the large rectangular room.

An acoustic environment that favors a large pipe organ is not the best for a slide lecture (unamplified live music is best in a fairly reverberant space, whereas sound amplified through speakers demands a “dry” acoustic with very little resonance), so the original auditorium design provided a way to adjust the amount of reverberation. Heavy cloth curtains could be pulled out along the walls to dampen the reverberation, or stored out of the way to make the space more resonant. This adjustable curtain system was situated behind the vertical wooden ribs along the sides of the auditorium flanking the stage and along the side walls in the seating area. The gaps between the ribs were open in these sections, making the wall acoustically transparent while retaining the visual unity of the space. It seemed a resourceful and ingenious way to meet both visual and aural objectives. But there were issues.

Some sound frequencies seemed to bounce around and amplify wildly while others dropped out almost completely, with the position of the dampening curtain seeming to have relatively little predictable effect. After numerous experiments proved fruitless, the museum and its designers came to the conclusion that the adjustable reverberation system just didn’t work, and the back sides of the acoustically transparent screens were covered with dark-painted plywood to try to create a solid acoustical surface. The ability to adjust reverberation was lost, but the problems diminished.

For the current renovation, Paul Scarbrough of Akustiks, Inc. worked with architects Westlake Reed Leskosky to analyze the sonic characteristics of the space in order to improve the auditorium’s acoustic performance. That research entailed setting up microphones inside the auditorium and measuring how long sounds of differing frequencies would reverberate—then figuring out why. “The biggest problems,” he recounts, “were with the wall surfaces. Unfortunately, when you take something like a wooden slat and space it equally along all the walls, you get acoustic anomalies. At the high end we found both destructive and constructive sound effects. In layman’s terms, that means that because of the mathematical relationship between the regular spacing of the slats, the depths of the spaces between the slats, and the wavelengths of different frequencies, some frequencies got canceled out by the walls and others were amplified.”

That explained the peculiar effects that were observed when the auditorium first opened. “They applied the plywood behind the slats, and that helped but it created another problem because the plywood absorbed the lower frequencies. Overall, the room did not have as much reverberation as you would prefer for unamplified music.” 

Organist Karel Paukert, who was the museum’s curator of musical arts for 30 years from 1974 to his retirement in 2004, adjusted his playing to the conditions. “The space was once aptly described as having ‘an atmosphere of distilled comfort,’ which is a nice way of saying it was a bit antiseptic,” he says. “I found myself taking faster tempi, using a different touch and stop colors than I would have in a venue more sympathetic to organ music. The sound decay was too rapid.” 

At the same time, the space proved to be a bit too “live” for amplified sound, with the measured reverberation times landing in a sort of no-man’s land between the desirable numbers for live music and amplification. Because the repeated vertical pattern of wall slats was at the root of the acoustical difficulties, the designers had to come up with an approach that would do away with the problem but still be visually compatible. Architect Ron Reed sums up the challenge: “Breuer had an idea that this would be a ‘tunable’ space, but anyone who attended any performance there would agree that it just had a kind of muddy quality. Nevertheless, that auditorium is a very important point in Breuer’s canon. It’s unique, and not a typical formal system for him, with so much wood and the relentlessness of it—much more like something you would expect to see out of Scandinavia of that era. There was a kind of visual warmth to the space, with every surface covered in this wood that had darkened with age.

We felt it was important to preserve the spirit of the design, because it was a special moment for Breuer. We went through a series of ideas and came to the realization that we had to reverse the figure-ground relationship. We would go from primarily opaque surfaces with a little bit of transparency to primarily transparent surfaces with a little bit of opacity. From bigger slats with smaller gaps to the other way around. It’s kind of a trompe-l’oeil, but it fixes the acoustics while preserving that relentless visual rhythm. It took a long time to get to this, because visually the hall is such a minimalist statement. It’s easy to be additive in architecture, much harder to be reductive and solve the problem in the simplest way.

“You want to be respectful of the spirit but not necessarily just replicate what was there before. Even if we could have corrected the space without changing it visually, the expectation created by the memory of how it used to sound—a memory evoked by how it looks—would color your perception. So it’s good to have some visual clues that things are different. You eat with your eyes first. The idea in this kind of project is to build some of the memory into the design but simultaneously reimagine it. If you can do those two things in balance, then you’ve really got something.”

The result is a revised wooden screen along the walls, behind which is a system of movable curtains that allow the reverberation to be fine-tuned to match the nature of the performance. “The screen is effectively sound-transparent,” says Scarbrough. “We restored the variable acoustic behind it, so for the organ or a string quartet, the curtains are stored in order to create a more resonant space, but they can also be fully or partially deployed to reduce reverberation.”

“The ceiling is also acoustically transparent,” Reed adds. “In a concert hall you want as much volume of space as possible, and Paul Scarbrough discovered that there was a tremendous amount of additional volume above the original wooden ceiling. We settled on a perforated metal ceiling that helps the auditorium visually by brightening it up a bit, and lets the sound through to make the most of the volume of space.”

 

Construction

More air, less noise New air supply and ventilation ducts of larger diameter move a higher volume of air with less noise. Sound-absorbing curtains hang from the metal track, allowing acoustic resonance for the solo flute of Joshua Smith or amplified surround-sound for Raiders of the Lost Ark

 

Other changes visitors will notice include new seats, a new aisle configuration intended to improve sight lines, and an extended stage. The deeper stage required removing a few rows of seats at the center front of the room, slightly reducing the total seating capacity of the auditorium but greatly expanding the range of performance styles. 

“The renovation will greatly enhance the pleasure of listening and seeing events,” says Massoud Saidpour, director of performing arts, music, and film. “Vastly improved and adjustable acoustics will allow the musicians to hear themselves better and perform better, and audiences will experience a more focused and refined sound. New audio equipment provides much better distribution of amplified sound, and with new theatrical lighting and an extended and sprung stage floor, events are going to sound and feel wonderful no matter what the nature of the presentation might be.”

A variety of events scheduled for this winter and spring showcase the renovated Gartner Auditorium (see page 17), but the work is not yet quite finished: tuning of the McMyler Organ, which requires a clean and dust-free environment, will be completed during the coming year by Cleveland’s Holtkamp Organ Company.  


Cleveland Art, January/February 2010