Good or bad acoustics have a significant impact on productivity, employee satisfaction, and health.
By Kenneth W. Betz, Senior Editor
Unwanted sound, or noise, is a major consideration in workplaces where employees function in close proximity, often with different expectations and needs regarding the acoustics of the space.
Dr. Gary Madaras, acoustic specialist, Rockfon, Chicago, pointed out that 90% of an organization’s operating costs are staff related. At the same time, 62% of the time people need to do quiet work. In other words, good or bad acoustics affect 90% of a company’s resources 62% of the time.
“Occupant noise from inside and environmental noise from outside the building can make it hard to concentrate,” he continued. “From the company’s perspective, the effects of noise are: decreased productivity, errors, inefficient use of resources, and ultimately, worsened financial performance. From the perspective of the staff, uncontrolled noise can increase stress levels, heart rate, blood pressure, respiration rate, and muscle tension. Under these physiological conditions, they are more aggressive, impatient, nervous, and less likely to help others.”
Sound isn’t the problem per se. Not all sounds are distracting. Speech noise is the most distracting commonly encountered form of sound in the workplace, mainly because someone else speaking interferes with one’s own internal monologue. When speech is intelligible it’s very difficult to ignore. The main negative effects of uncontrolled speech noise are worker dissatisfaction, decreased employee productivity, and compromised personal and company security, Justin Stout, director of market development, Cambridge Sound Management, Waltham, MA, observed.
Stout also noted that insufficient speech privacy is the number one driver of employee dissatisfaction, according to recent studies. Additionally, employees waste at least an average of 21.5 minutes a day due to speech distractions, which is equivalent to roughly 4% of an 8-hour workday.
In terms of personal and company security, a whopping 53% of employees report having overheard confidential company information at the office. The lack of speech privacy can result in compliance and legal concerns when workers are discussing private customer information such as finance or healthcare records, he warned.
Disruption of employee workflow also is cited by James Johnson, commercial segment manager, Armstrong Flooring, Lancaster, PA, as one of the most significant impacts of uncontrolled sound. “According to Univ. of CA Irvine research, employees are interrupted on average every 11 minutes. This adds up financially as unproductive time for businesses,” he said.
Uncontrolled sound in the workplace could be the very reason employees look for employment elsewhere, commented Robert Marshall, technical services manager, CertainTeed Ceilings, Malvern, PA.
“People tend to feel tired and stressed in noisy environments, which can lead to higher rates of absence. We should no more design and build office environments where acoustics are poorly controlled or left to chance than we should allow temperature, lighting, or any other indoor environmental quality to go unaddressed,” said Niklas Moeller, K.R. Moeller Associates Ltd., Burlington, Ontario.
Just as some acoustics experts make a distinction between sound and noise, the latter being unwanted sound, Moeller makes a distinction between quiet and silent.
“Though many people tend to use these words interchangeably, there’s a subtle difference that provides key insight into acoustic design. A silent space is one that has low or no sound at all, whereas a quiet space is one with little or no unwanted sound. In many cases, project teams attempt to provide quiet by designing for silence. In other words, they try to eliminate all sound from the space. However, this goal has the unintended result of making any remaining sounds that much more disruptive to occupants. And, in a workplace, sounds will definitely remain. If the goal is to design for quiet instead of silence, it’s easy to see that adding a comfortable level of background sound is desirable in that it helps cover unwanted noises and reduces their disruptive impact,” he explained.
The Open-Office Challenge
Open offices reflect the current trend in office design, but the spaces have two major strikes against them, Moeller observed. First, occupant densities tend to be higher. Second, there’s little or no physical separation between employees. As a result, expectations regarding some aspects of acoustic performance have to be lowered and greater attention has to be paid to remaining details. Otherwise, employees will be “acoustically exposed” and perhaps begin reaching for headphones to the detriment of the intended collaboration.
Moeller cited a Gensler (San Francisco) survey that shows that the facilities that rate highest for collaboration are actually those in which the individual workspaces are designed for focus work. “It makes sense,” he said, “because people typically feel far more comfortable talking when they aren’t disturbing—or being overheard by—those in a wide radius around them. In other words, impromptu conversation is supported by providing a measure of acoustic isolation. To boost performance within an open plan, designers can implement greater levels of absorption and install a high-performance sound-masking system.”
Rockfon’s Madaras noted that one does not expect to achieve sound privacy in an open space with others in close proximity. “For sound privacy, one must move into a well-built enclosed room or ensure that no eavesdroppers are close by,” he said. “The acoustic goal in open office spaces is not sound privacy, but instead to attenuate distracting noises such as conversations as much a possible so that only a limited number of people are negatively affected. Strategies for limiting the propagation of noise include highly sound-absorptive ceilings.”
Standards and design guidelines, such as the WELL Building Standard, require that ceilings in open offices have a minimum Noise-Reduction Coefficient of NRC 0.90. Madaras suggested adding even more sound absorption using carpeting/tiles on the floor and sound-absorbing/blocking workstation partitions to further attenuate distracting noises. “Layout of workstation partitions, if used, can also help to block direct lines of noise propagation between workstations or between communal areas and workstations. However, the use of workstation partitions is becoming a thing of the past,” he said.
As design trends lead open offices toward having hard floors, no walls or partitions, and plenty of glass, the best approach is often a highly sound-absorptive ceiling and electronic sound masking, Rockfon’s Madaras suggested.
If a room contains many reflective surfaces, sound will amplify throughout the space, disrupting productivity, agreed Ryan Larkin, marketing communications coordinator, Acoustical Solutions, Richmond, VA. “In reverberant rooms, people tend to talk louder over one another when speech intelligibility is low. This can easily cascade throughout the space, disrupting everyone,” he said.
The ABCs of acoustic design are absorb, block, or cover, but with open offices, materials that block sound are deemphasized, meaning that more emphasis must be put on materials that absorb sound (such as acoustical ceiling tile, or clouds, and carpeting) or technology that covers it up (sound masking), according to Cambridge Sound Management’s Justin Stout.
“Designers can pull together a holistic solution to include acoustical ceiling tiles and partitions,” agreed Armstrong Flooring’s James Johnson. “The partitions reduce visual disruptions and the acoustical ceiling tiles, in tandem with the partitions, reduce the airborne sound transmission.”
Ceiling treatments seem to be the element with which most people are familiar when it comes to acoustic design, but they’re only one aspect. “While they contribute to a workplace’s overall performance—primarily by adding absorption—they simply can’t tick off all the required boxes. The easiest way to put together a basic checklist is to refer to the ABC rule,” noted Niklas Moeller.
He continued, “Absorption is needed to reduce reverberation and noise levels. Blocking is used to help stop the spread of noise from one area to another. Cover refers to installing a sound-masking system, which controls the workplace’s background sound level. If a project team only uses one strategy or solution, they might believe they’ve placed a checkmark next to ‘acoustic performance,’ but in reality they’ve only addressed one aspect of it and, in doing so, may in fact have made other aspects worse. Each element of the ABC rule is necessary to meet speech-privacy needs and control noise, but insufficient on its own.”
Ceiling treatments work well because they can be used to create pseudo partitions around a desk space, work area, or in an open retail space, according to Ryan Larkin of Acoustical Solutions. These treatments can include ceiling clouds that hang horizontally, baffles hung vertically, or materials, such as acoustical foam and fabric-wrapped panels, mounted directly to a ceiling.
In addition, Larkin suggested that wall panels can help reduce the sound throughout a room by eliminating wall reflections in the areas they are installed. They may be customized to provide an absorptive desk partition, tack board, or hung as art with printed images.
He also noted that desktop sound masking is often used in open-office environments to camouflage conversation by decreasing speech intelligibility. However, this only covers up or masks the speech. It does not improve the sound quality within the space, he added.
Justin Stout of Cambridge Sound Management, suggested providing isolation booths, often called huddle rooms, team rooms, phone rooms, or focus rooms. The idea is simply to provide a space where employees can retreat for focus work, private meetings, or phone calls.
CertainTeed Ceiling’s Marshall mentioned the availability of acoustical gypsum. “An entire wall can be constructed of acoustical drywall and every square inch becomes a sound absorber rather than the limited placement options for wall panels,” he said. “There are many products and options, but most renovation decisions depend on how involved or disruptive the project can be. With new construction or major renovations, everything is in a bag of available tools to use,” Marshall concluded. Sound experts would urge designers to use all of those tools. CA
Unwanted Sound? Mask It
Sound masking, adding a low level of unobtrusive background sound engineered to protect confidentiality and reduce distractions by reducing the intelligibility of speech, is one of the solutions possible in open-office environments.
Background sound levels are a key consideration when planning and evaluating acoustic performance, and sound masking is the only way to accurately raise and control those levels, explained Niklas Moeller of K.R. Moeller Associates, Burlington, Ontario.
“Its role is well recognized by the acoustical-engineering community, acoustic design standards, government guidelines, the LEED rating system, the WELL Building Standard, and others. In other words, this technology is ‘necessary,’ not ‘nice to have,’” he said.
Moeller went on to explain that a sound-masking system uses electronic components to generate a comfortable sound that most people compare to soft airflow. The sound is distributed throughout the workplace by a network of loudspeakers typically installed invisibly above the ceiling or within an open ceiling. Sound masking doesn’t absorb, block, or cancel noises, but rather interferes with an occupant’s ability to hear them, much like it’s difficult to understand someone talking to you from a distance when, for example, you have a water tap or a fan running.
To perform well, the system has to be designed so that it can be tuned, Moeller continued. It should offer small control zones no larger than three loudspeakers in size. Exceeding this limit will quickly reduce the technician’s ability to adjust the masking sound, necessitating compromises between masking performance and occupant comfort. For that reason, each small zone must also provide precise volume control and third-octave equalization over the entire masking spectrum, which is typically specified between 100 and 5,000 Hz, or as high as 10,000 Hz. Post-installation, the system must be tuned. This process involves measuring the output within each control zone and adjusting it to meet the desired spectrum.
Compromises in design or tuning can reduce performance by as much as 50% in unpredictable locations across a space, Moeller warned. “The challenge for the client is that it’s very difficult to subjectively assess masking performance, so it should be well specified in advance. It’s strongly advisable to require a detailed report of the tuning results—one that clearly indicates the desired curve has been met throughout the workplace and identifies the few areas that might remain outside spec and why,” he said.
Sound masking can effectively cover or mask low-level noise. “It doesn’t stop the noise; it just prevents people from hearing it, which can be equally effective,” Chicago-based Rockfon’s Dr. Gary Madaras said.
He explained that loudspeakers are distributed throughout open-office areas and enclosed offices (especially those adjacent to conference rooms). Sound masking is not typically used in rooms where speech intelligibility is important, such as conference rooms. A broadband, low-level (40 to 45 dBA) masking sound is played constantly through the loudspeakers. “Many people sleep with a fan on even in the winter. It’s not for thermal reasons. The constant sound from the fan masks the cars outside, creaks in the house, and other disturbing sounds,” he said.
Masking can be added to an environment through speakers, either installed in the ceiling or in the plenum, and sometimes even under the floor, according to Justin Stout of Cambridge Sound Management, Waltham, MA. “Sound masking essentially reduces the area where someone’s conversation is distracting by a factor of three. So, if a worker used to be able to hear people clearly at 45 to 50 feet away in an open environment, adding masking will make it so he can only clearly hear the people within 10 to15 feet and conversations at a larger distance fade into the background,” he explained.
If a space is under-designed, the masking volume may be too intrusive and become an unrequested insertion of noise, Malvern, PA-based CertainTeed Ceilings’ Robert Marshall, warned. However, when the sound absorption is appropriately coupled with sound masking, the system creates an acceptable level of speech privacy by reducing the size for the circle of unwanted intelligibility. With properly coordinated sound masking, you can understand what someone is saying close by, but only if you want to, and as such, [masking] often improves the capability to concentrate, he explained.
Marshall pointed out there are several options when it comes to sound masking. One option is to put the generator of the masking noise in the plenum of the ceiling. However, this may cause you to increase the output of the sound masking that may be unnecessary for the occupant only because the noise is working against all the other elements above the ceiling. The other option is direct sound masking that is installed within the ceiling system itself and looks like sprinkler heads. This system projects noise down at measured locations. Both are very effective for masking noise. “All in all, nothing by itself is the sole solution. A marriage of different aspects within a design is best in order to create a good acoustical solution,” Marshall concluded.
To Control Or Not To Control?
Sound control or the decision to not control it is very much part of the retail sales strategy, observed Dr. Gary Madaras of Rockfon, Chicago. “Often, food-and-beverage establishments consciously decide to have noisy spaces,” he continued. “The less people can talk, the more they drink and eat. Studies show that sips per minute increase with an increase of noise level. In other words, if you want to sell more alcohol, turn up the music. As noise levels increase, so does the average number of table turns, so restaurants see an increase of sales with an increase of noise levels.
This strategy does not work with all types of retail settings. Conversely, when airports decrease noise levels in concourses, retails sales increase. People decide to linger longer, have a shoulder massage, have dinner, and buy some gifts instead of running immediately for ground transportation. Each retail setting is different and requires definition of the potential buyer, the buying cycle, and how sound affects the buying experience,” he said.
But, having proper acoustics in a non-restaurant retail space is a key component to improving the shopping experience. Providing good customer service is dependent upon effective communication with the client. If the room is too loud or noisy, the customer may feel uncomfortable, become tired, and choose to leave or shop elsewhere. They may also have a hard time hearing what is said. A proper acoustic environment allows conversation to take place easily, according to Ryan Larkin of Acoustical Solutions, Richmond, VA.
On the other hand, not all shoppers want or need a tranquil environment. “In retail environments and large, big-box stores, we don’t often find sound control to be an issue as the store owners and patrons alike both want background music and a sense of liveliness in the space,” said Cambridge Sound Management’s ( Waltham, MA) Justin Stout.
This depends on the type of retail and the demographic of the patrons he went on to explain. “There are times when noise buildup is a problem and the clarity of music suffers greatly, but it is rare that owners want to spend the money to add acoustically absorptive materials. In many public shopping malls and grocery stores noise buildup can be a problem; however, most of the time this is neither unexpected nor warrants any action, he said.
Stout added, “We do find that there are many retail environments where sound masking can add a benefit. Cambridge Sound Management has done some installs at mobile-phone stores, retail banks, pharmacies, and even car dealerships, adding masking in areas to protect speech privacy where confidential customer information is discussed. We also have our product in many hotels and spas to help cover up unwanted noise and help guests relax.”
Sound-control needs vary greatly, depending on the goals of the establishment. Restaurants that are primarily focused on high turnover won’t need to create a warm acoustic environment. Retail environments are usually more focused on the volume within the space rather than creating a design-centric location with sound control, CertainTeed’s (Malvern, PA) Robert Marshall commented. “However,” he said, “there could be alternative goals within each of these spaces that pose more of an acoustical need. If a grocery store has a coffee bar that encourages conversation and/or a quiet space in which one can work peacefully, then acoustics could be taken into greater consideration within that designated space.”