A theater or auditorium may not be the first place you would expect to see a lot of metal. However, in its mesh form, or as metal ceiling panels, metal can perform either as a modern and contemporary decoration or as an effective acoustic control solution.
Metal components play an important design and performance role in creating a dynamic theater environment
Due to its natural properties, notes Aleks Couturier, assistant business manager-architecture and design at W.S. Tyler, St. Catharines, Ontario, Canada, metal mesh is an excellent sound conductor. Alternatively, she says, it can also be used as part of a sound absorption system. “Wire mesh is unique because of the ability to shape and curve it in very specific ways. The curvature of the finished surface allows sound to bounce off the mesh in a targeted manner. Placing wire mesh in strategic locations throughout a theater or auditorium allows operators to give guests a superior auditory experience from almost any seat in the house. Depending on the usage of the mesh, it can enhance the acoustical sound quality or it can act as a sound absorption barrier.”
Michael Link, business development manager, and Roger Kahl, technical product engineer, ceiling systems, at GKD-USA Inc., Cambridge, Md., notes that the biggest impact of metal mesh in acoustical design lies in not having any impact at all. “Most mesh types used in architecture are acoustically transparent. Only very few meshes with little open area can reflect or scatter sound. While solid structures have reflecting or absorbing characteristics, this property of metal mesh enables acoustical designers to tailor the needs for sound reflection, absorption, or scattering to the geometry and use of the room.”
Reverberation and Acoustical Design
Reverberation time is the most important dimension in acoustical design. “It measures the time that passes until the sound level has dropped by 60 dB,” explains Link and Kahl. “The reverberation time is largely dependent on the sound absorption capacities of the surfaces in the room-walls, ceilings, floors, furniture, as well as room volume-influence the sound characteristics. While metal mesh can be used to conceal hard surfaces in areas where reflection is needed, it is generally used in combination with sound absorbing fabrics, porous absorber materials like mineral wool or foam materials, or resonance absorbers.”
“The goal is to create uniformity across the audience plane and support back to the speaker/performer,” says Gary S. Madaras, Ph.D., Assoc. AIA, manager, acoustic strategies at Chicago Metallic Corp., Chicago. “Speech intelligibility results from a quiet room, strong, early, high-frequency reflections off the ceiling and controlled mid- to low-frequency reverberance. Metal panels inherently reflect the high-frequency sound that is so important for speech intelligibility. As frequency decreases, wavelength increases, and the sound transmits more easily through the metal to get absorbed in the space above the ceiling panels or by sound-absorbing material positioned behind the metal surface.”
Whether or not metal ceiling panels should be perforated depends on where they are located. In areas that reflect sound directly back down to the audience, the metal panels should not be perforated, as the reflections are important for speech intelligibility. “If the room has a fixed or typical sound source location (e.g., stage or speaking platform) and fixed or typical audience location (e.g., theater style seating), then the metal ceiling panels over the sound source and out to a point about half way between the source and furthest seating location should not be perforated,” explains Madaras. However, when metal panels are located along the side walls and back half of the theater, perforations allow them to absorb sound at all frequencies. “Reflections off these areas of the ceiling only add to late arriving reverberation, interfering with speech intelligibility,” he adds.
Sound Absorption Performance
For sound absorption performance in metal ceilings, Joerg Hutmacher, sales manager/vice president at Minneapolis-based pinta acoustic inc., notes that perforated metal, expanded metal or linear metal with sound absorptive backers are needed. Those can be non-woven acoustic fabrics, acoustic foams or encapsulated fiberglass. Backers are also recommended in areas where echo or reverberation is an issue. “Metal ceiling tiles are used without backers in large open areas where an edgy or modern look is desirable, such as an entry to a theater,” Hutmacher says. “That said, there are a lot of options to meet aesthetic desires without sacrificing acoustical requirements. Unique solutions may include some metal ceiling tiles with acoustical backers and some without. Additional custom looks include a combination of rows or clouds of metal ceiling tiles without a backer combined with rows or clouds of ceiling tiles with acoustical control.”
There are a number of simple ways to achieve damping. Madaras says a common solution so the holes can’t be seen through is perforating the metal panel and gluing a black material on the back, which achieves adequate damping in a lot of situations, and provides moderate sound absorption. In theaters, however, he notes that perforated panels are usually perforated to obtain higher sound absorption, and require a fibrous matt (e.g., fiberglass, mineral wool, etc.) behind the panels to provide excellent damping and sound absorption.
Shannon M. Weir, marketing manager for architectural specialties at Armstrong World Industries, Lancaster, Pa., notes that typically absorption is put in the rear of the theater, while diffusers/reflectors are put overhead and on the front walls. “This is done to project the sound from the stage around the room, but then absorb it in the back so it doesn’t come back. This would mean solid and curved panels would be a good fit for over the stage and perforated panels with acoustical fleece and an acoustical infill in the rear of the theater.”
Design Aesthetics
It’s important to understand the theater’s technical requirements before beginning the ceiling’s aesthetic design. As Madaras notes, this includes any loudspeaker locations, and the opening requirements in the ceiling, so the sound from the loudspeakers is not blocked, as well as understanding catwalk and follow spot locations, upstage/downstage sightlines, stage aprons or thrust stage, and overhead rigging requirements. “All these things can potentially chop up your ceiling aesthetic beyond recognition if not accounted for from the beginning,” he says.
In addition to acoustic control,Ann Smith, manager architectural business development at Cambridge-based Cambridge Architectural, notes that metal mesh can provide a durable and unique aesthetic solution to theaters. As a decorative solution, metal mesh can provide a specific look or texture to the theater design, while allowing the acoustical paneling to be changed as required for a specific performance, without changing the look of the concert hall itself.
Additionally, metal mesh’s durability allows it to function as a wayfinding device in a theater when draped to form a hallway. It’s transparency, Smith notes, allows it to be used to guide foot traffic through a concert hall. And, when used as wall cladding, metal mesh can protect surfaces against denting and scratching.
Playing with lighting is another way to let metal mesh shine in theaters. “Lighting is a beautiful combination and a beautiful marriage with mesh,”Smithsays. Lighting on metal mesh screens can be ambient, keeping the mesh transparent, or when shone directly onto the mesh, it can become opaque. Lighting designers can even play around with different color themes, or flash images onto the mesh. In a very closed space, Smith notes that lighting is more controllable since you’re not fighting with daylight. “It’s a controlled space when it comes to lighting, so there’s a whole plethora of things that a designer could do with lighting to give a different look, or a different feel, even tie it into the performance potentially.”
“Theaters should be an unforgettable experience for their visitors,” says Link and Kahl. “Although necessary for the function of theaters, this experience should in no way be compromised by disturbing structures and installations which could impair the architectural image. Metal mesh systems do a lot to help architecture to preserve the appearance: disguising technical structures, creating roomy shapes while allowing free air flow, creating areas of vivid light reflections and colors, but also enhancing comfort by controlling room acoustics, etc.”