Acoustic hot spots diffuse sound and enhance design in open plenum environments.

Open plenum ceiling designs offer dramatic visual appeal for everything from office buildings to schools and hospitals. But while satisfying the eye, the ear sometimes suffers as wide-open spaces and hard surfaces can cause sound to wander unchecked, invading concentration, conversation and privacy. A unique solution is to create one or multiple acoustic “hot spots,” a quiet oasis where sound is softened and confined to specific areas within the larger open space. Like a true oasis, these acoustic hot spots offer both comfort and beauty, serving as functional, and highly unique, design elements that add personality and character to interior environments.


An acoustic hot spot is essentially a creative sound barrier-one that takes an imaginative approach to keeping unwanted high-frequency noise out, while diffusing the lower-frequency sounds coming from within. It can be accomplished by positioning acoustic panels above the area where sound needs to be controlled. But when you think about acoustic panels, don’t think square and white. Think clouds and canopies, circles, triangles and flying carpets in a range of materials, a rainbow of colors and unlimited configurations.

Imagine a hospital ER with an open plenum ceiling design. While the open design creates a feeling of spaciousness in what is frequently a crowded, bustling environment, privacy is also imperative, especially at registration desks, intake areas and doctor/patient consulting areas. An acoustic cloud or canopy over these specific areas can create the quiet and privacy needed, while adding to the aesthetics of the overall interior. The same thing can be accomplished in office areas, whether the sound attenuation needed is for a handful of workers, or for 50 or more. 


In today’s economy, building owners are increasingly concerned about controlling costs. That applies to all areas that affect the bottom line, from capital expenditures to employee productivity. The creation of acoustic hot spots can help architects, builders and designers meet their clients’ financial objectives.

If an acoustically well-designed environment is essential for employee productivity, the design tendency may be towards a traditional acoustical ceiling. The fact is that an open plenum design with acoustic hot spots can satisfy the need for both increased quiet and decreased construction costs. In fact, multiple hot spots can be constructed at a lower cost than a full acoustical ceiling.

A full acoustical tile ceiling requires perimeter treatments, a full suspension grid system, and numerous tiles- factors that drive up costs for both materials and labor. On the contrary, acoustical hot spots are easily installed with minimum materials. Each cloud, canopy, tile or other acoustic shape is easily suspended with a few wires. Even in large office areas requiring multiple hot spots, the time, labor and material costs will be significantly lower than for a traditional ceiling.


For many architects and designers, the choice of an open plenum design goes beyond pure aesthetics. It also provides the functionality and accessibility needed as technology advances. The open design allows easy access to wiring and cables for fiber optics and other communications and information systems. As these technologies change or systems are expanded, the open plenum enables faster updates and reconfigurations-with less disruption to office areas and lower construction costs than might be involved in removing and replacing ceiling panels. With the possibilities of acoustic hot spots, the functional advantages of the open plenum can be achieved, without sacrificing acoustic benefits.


So, how do you design an acoustical hot spot? First, it’s important to understand how sound is measured and controlled.

Sounds are vibrations from various sources that are conducted by any elastic material. Known as conductors, these materials are classified into three groups: solids, liquids and gases. Air (a gas) conducts sound slowly, while liquids do so at a more moderate rate, and solids at a faster rate. Sound is heard in two ways: reflected and direct. The human ear picks up direct sound faster than it does reflective sound.

The basic function of acoustical materials is to control these sounds. They can keep unwanted sounds out, provide privacy by keeping sounds contained, or control noise based on their orientation and composition. All materials have the ability to reflect or absorb sound. Solids, such as glass and masonry, typically absorb less than five percent of sound, while reflecting the rest, sending sound waves back into the environment. Acoustic products can absorb up to 100 percent of sound waves.

Of course, the science of sound control is much more involved and technical than simply knowing which materials are most effective in absorbing and reflecting sound. In most cases, it’s best to rely on the expertise of an acoustical consultant. A consultant can measure how much absorption exists in a room, due to carpets, glass, furniture, people, and other factors, using established measurable criteria (ASTM). A technical recommendation can then be provided based on the sound objectives for a room or specific area, ranging from “dead” to “live” to “moderate.” In this way, targeted areas can be designed with spot on accuracy that enables the creation of hot spots perfectly suited to needs for privacy, speech intelligibility and individual productivity. A variety of materials can be used to accomplish the ideal acoustic environment, including fabric and foam materials, perforated metal and wood wall and ceiling panels, special design diffusers and baffles.


If an open plenum ceiling is your first choice for a building interior, the potential offered by the hot spot concept means you no longer need to sacrifice acoustics for aesthetics and functionality. On the contrary, the availability of acoustic panels in a wide range of materials, shapes and colors offers an oasis of new possibilities in creativity, sound control and cost effectiveness. Acoustic hot spots are a sound choice-and the advantages are no mirage. W&C