University of Iowa Voxman Music Building’s Theatroacoustic Ceiling System

 
January 8, 2018
After much of the University of Iowa's campus was ravaged by a flood in 2008, the institution's School of Music decamped from the riverbanks to downtown Iowa City, where it got a prominent site and upgrade in technology. From the organ hall to rehearsal rooms, every space in the 184,000-square-foot Voxman Music Building, designed by Seattle-based LMN Architects with local firm Neumann Monson Architects, features custom acoustical systems, the result of an intensive collaboration between architect, acoustician, and machine.

The most complex of these systems hovers more than 30 feet above the 700-seat concert hall, a long rectangular space on the second floor of the six-story building. LMN Architects worked with acousticians at Jaffe Holden, in Norwalk, Conn., and other consultants to design a theatroacoustic ceiling, an undulating element of aluminum composite panels.

LMN Architects used parametric modeling to integrate acoustic reflection, stage and house lighting, audiovisual elements, and fire suppression into a single eye-popping ceiling system. The reflector features an aesthetic, seemingly random, but highly specific pattern of geometric openings that aim to blanket the room evenly with sound while also providing spaces for things like audio speakers.

Following in-depth conversations with the acousticians, the design team, which included architects at LMN Tech Studio, an internal group of designers at the firm who specialize in emerging computer technologies, began by building acoustic analysis tools in Grasshopper and using ray-tracing, which are common in light studies but also helpful for approximating the behavior of sound waves. The tools "were admittedly crude," says LMN Tech Studio associate Scott Crawford, "but they allowed us to have conversations with the acousticians that we might not have otherwise had."

The parametric model allowed the architects to target where sound would be reflected and where it would be absorbed, passing through the reflector's openings. Beyond lighting and fire suppression purposes, many of the openings helped achieve acoustic balance. The architect's rough models were sent Jaffe Holden for advanced analysis and refinement.

"By extending the reflector to cover the entire room, we could actually create reflectors in areas of the room where the acousticians normally wouldn't," says LMN Architects partner Stephen Van Dyck. For cost and aesthetic reasons, sound reflectors are often limited to the area above the stage. "But when it's all a part of this same system, by having that perimeter become reflective, it allowed us to envelop the audience in the sound," Van Dyck says, adding that the Jaffe Holden team were thrilled to discover they "could make the edges acoustically opaque" and reflect sound from the room perimeter in novel ways.

The perforated ceiling comprises a series of triangular aluminum composite panels, no two of which are alike despite appearing symmetrical. Each panel, the largest of which is 5 feet on a side, features a side tab that connects it to a series of transverse steel ribs hung from the room's rafters. A CNC machine cut the 0.33-inch-thick aluminum composite panels and scored the tabs, which were later hand-folded. Each panel was given an alphanumeric coordinate—for example, B.17—to indicate its position in the ceiling's triangular grid. Each bolted connection in the system required a neoprene washer for acoustic isolation.

Van Dyck says the folded tabs also serve to control the "psychoacoustics" of the room. "Musicians tend to project what a room should sound like, and that's sometimes what they hear, as opposed to the actual acoustic," he says. The project's acoustician was concerned that performers, upon learning the reflector was made of aluminum versus wood or composite panel, would say the room sounded "tinny." The tabs help by giving the ceiling a perceived thickness. The architects also selected an extremely matte painted finish for the reflector.

Before construction began, LMN Architects built a 1:3 scale mock-up of a portion of the theatroacoustic ceiling, which helped convince the client that the ceiling system could be fabricated and installed successfully. "You really put all the doubts to rest in a room full of contractors and owners and consultants when you can walk into the meeting on a Monday morning and say, ‘Hey, we built this over the weekend,' " Van Dyck says.

The Voxman Music Building asserts new possibilities for parametric design tools with regard to a building's performance. As the building industry slowly comes more to resemble the manufacturing industry, these tools "bring the conception of what it means to design a space and the making of it much, much closer to each other," Van Dyck says. "The fact that the same information that we used to build chipboard models and mock-ups in our office was the information used to drive the machines and fabricate the ultimate building is a microcosm for this whole process in the future."

Architect Magazine
Story by Timothy A. Schuler