Poor acoustics in existing spaces have a variety of solutions.
A well-informed architect or interior designer involved in new construction has an infinite variety of products available to create an acoustically optimized space from the ground up. Unfortunately, not every new space is built according to acoustically enlightened principles, leaving thousands of offices, classrooms, restaurants, and other spaces with poor acoustics and sound control, giving occupants and owners a headache.
It can be difficult to fundamentally change the way a built space behaves acoustically. HVAC systems aren’t easily replaced or rerouted. Trendy finish materials won’t be abandoned, even if they turn a café into an echo chamber. The addition of a wall-to-wall suspended ceiling is rarely practical. However, there are steps that can be taken to address noise issues in existing spaces with limited disruption to the occupants and the operating budget.
A number of tests can be performed to determine whether a space meets the requirements of acoustic comfort. These can be performed by professional acousticians, but technical support teams for acoustic ceiling and wall manufacturers also have the appropriate expertise and equipment to test your facility.
The two most practical measurements are reverberation time and background noise.
Reverberation Time (RT) is time required for an average sound in a room to decrease by 60 decibels, once the source has stopped emitting a sound. It is expressed in seconds. RT can be calculated mathematically based on the volume of room and the square footage of sound absorbing surfaces within it, or it can be measured with a sound-level meter.
Background noise is the noise level in a space measured when the specific noise being studied is absent. Major sources of background noise are HVAC noises, outdoor noises, reflected speech sounds (echo), and noise from adjacent spaces. Background noise is usually expressed as dBA, a measure that reflects the response of the human ear, which is less sensitive to low and high frequencies.
Reverberation vs. Absorption
Sound reflects readily off of hard surfaces, as relatively little energy carried in the sound wave is absorbed into the surface material. As reflection builds upon reflection throughout a room, a web of competing sound waves gradually decays as it is absorbed bit by bit into the exposed surfaces in the space.
Reverberation is an increasing problem due in part to some current interior-design trends. Hard-surface floors, the move away from fabric-covered cubicles, glass walls and partitions, open plenums, and exposed structures all add to the reflective surfaces, increasing reverberation times.
Acoustically absorbent materials, such as high-density fiberglass clouds, baffles, and direct-to-deck ceiling and wall panels are extremely effective in reducing reverberation time.
When speech privacy is a specific concern, such as in an open office setting, acoustic masking can be added alongside absorbent installations. This involves introducing finely tuned volume and frequency signatures that fall within the acoustical range of human speech. It doesn’t eliminate speech sounds, but rather it reduces the physical zone of speech intelligibility by blending in with them.
Calculating the precise amount of sound absorption in a space using the sound-absorption coefficient for each material multiplied by the surface area of that material, then finding the sum of all absorptive materials in the space is more math than anyone but professional acousticians care to do on the subject. Fortunately, there are some general rules of thumb that can be followed to determine how much sound absorption is needed in a given space based on the form the acoustic material takes. Each form has its advantages, depending on the design concerns and structural realities of the space requiring remediation.
Direct-to-deck acoustic panels, which can be glued or screwed directly to the ceiling structure without wires or grid, are one of the simplest ways to improve acoustics in existing spaces. Their versatility and ease of installation maximize sound absorption while minimizing disruption to occupants.
Because of their minimum overall system depth, they can be attached to low ceilings or even angled ceilings. Full-coverage installation can mimic the clean look of a traditional drywall ceiling while providing the acoustic benefits of a suspended ceiling. They can also be installed in fields or as single panels. With absorption levels similar to standard suspended ceiling panels, direct-to-deck solutions should be installed to cover as much of the ceiling area as possible.
Beyond ceiling height, the fire protection and suppression system in a given space can be a key factor in the selection of direct-to-deck solutions. Systems with pendant sprinkler heads can accommodate traditional suspended ceilings and direct-to-deck panels, but upright sprinkler heads require a solution with a shallower system depth, such as CertainTeed Ceilings’ (Malvern, PA, certainteed.com) Ecophon Focus B, F, or SQ.
Clouds & Baffles
Because free-hanging clouds absorb sound from both sides—direct from the source as well as sound reflected from the deck above—they offer the most efficient sound absorption option. Installation is extremely flexible, allowing clouds to be placed at varying heights, in tiers, and even angled. They can even be installed in addition to full suspended ceilings in particularly challenging spaces like open offices. Clouds are also offered in a wide variety of colors, shapes, and sizes, offering the freedom to work within the design aesthetic of an existing space. CertainTeed Ceilings Ecophon Solo clouds are available in 16 standard colors and 11 different shapes—everything from squares and circles to triangles and hexagons.
Similarly, baffles provide double- sided absorption, but with a smaller overall system depth than clouds. Baffles can also keep sight lines clear in high ceiling areas, maintaining the very openness that otherwise would add to the acoustic challenges.
Because clouds and baffles absorb sound from both sides, installing products equal to 40 to 60 percent of the square footage of the space will bring reverberation times down to comfortable levels.
Wall panels excel in smaller spaces with reflective walls such as conference rooms. Academic settings such as libraries and classrooms are prime candidates in that they often already have full suspended ceilings.
The design flexibility of wall panels has improved tremendously in recent years. Beyond simple 4- x 8-ft. panels, circles, squares, and rectangles in a variety of sizes and colors are now available. Ecophon Akusto One SQ wall panels can be custom printed, disguising the acoustic performance behind photos or artwork.
Where to begin? There are always multiple paths to solving noise problems in an existing space, but there’s no need to jump to the most elaborate or disruptive. It’s surprising how much can be accomplished with relatively simple fixes. Rather than dive in with extreme measures, start small with the least disruptive or invasive options. If that’s not enough, move on to the next solution. Whether it is a few simple wall panels, a field of direct-to-deck panels, or a collection of clouds, the right solution for the space is out there.