Acoustical planning provides effective environments.
Those of us who work in offices have noticed some significant changes in the look, feel and sound of the contemporary workplace. Not only have the physical aspects changed, but the way we interact with our space and everything within it has changed, also. The biggest of these is our ability to collaborate and communicate with one another: an ever-increasing component of what companies are requiring of their staff and firm culture.
The change in workplace design is not simply a departure from the hierarchy or “status” of private office to open office, but rather a continuum of change that companies are implementing based on leading guidance to design spaces that suit their own specific goals and culture, to drive change and to think ahead for the next generation of worker.
The Center for the Built Environment’s POE Survey research shows that, although most occupants of modern workplaces are happy with this new environment, acoustics (and more specifically, background noise and lack of privacy) scores consistently low in an otherwise high performing space. Although most research on the subject of workplace acoustics shows that the majority of people want a more controlled space in a quiet environment with less distraction, each individual is subjective in his or her own experiences and reactions to a busy space: One person’s annoyed distraction is another’s innovative environment. Our discussion here addresses how proper acoustical planning can provide variable, effective environments for a variety of workers.
Traditional Vs. New Workplace
The traditional approach to workplace design typically had a row of offices at the window line or building perimeter, with open work areas or smaller offices nearer to the core. This approach was all about barriers, some intentional and beneficial, such as the acoustical privacy provided by the use of drywall office construction, others not, such as the light-starved core of the building with no access to daylight or views.
Our friends in the architecture and interior design field lead the way for change long ago with open loft-like spaces, allowing for easy communication and the exchange of ideas. This philosophy, along with increasing awareness of the benefits of daylighting and views on occupants, has advanced the model workplace to a point where openness is expected, along with daylight and good indoor air quality. Air quality, in particular, has led to advances in efficient HVAC systems that, unlike their predecessors, no longer provide the typical “hum,” significantly lowering office background sound levels. This makes distractions from neighboring voices, elevator chimes, ringing phones or humming printers more noticeable and, for many, more bothersome. This is a big reason why discussions around creating an acoustically comfortable space must take place early in the design process.
The design of a new workplace is more than a matter of squeezing the most out of the real estate: It’s a matter of creating a real place, where comfort is a consideration and a diversity of space types allows for all of our different ways of working to be accessible and productive. An investigation of top companies by design firms, such as Gensler, led to the understanding that workers typically require spaces to accommodate four different work modes: Socialization, Learning, Focus and Collaboration (Gensler Workplace Survey 2008).
A key part of the Cerami design process is discussing what type of acoustical environment the users need to support their company goals. This diversity of space includes conference rooms for internal and external communication; desk areas for focused, thinking work; collaboration lounges for group work, and pantry or hub areas for socializing. These varied environments carry with them an expectation that each space will provide an acoustical environment to support the functionality required of its users.
Additionally, a common concern that our clients bring to us is how to communicate the adaptations that have been made to the design approach to bring thoughtful acoustical design to the process where staff comfort and productivity are equal parts of the process. We work closely with our clients to provide them with tools, such as acoustical models, auralizations and even mockups to let their staff understand the new environment and manage expectations.
Understanding Acoustical Criteria
The main acoustical requirement for private offices and conference rooms is voice privacy. In the modern workplace, private offices may not be a reflection of status, but rather a requirement of job function, such as Human Resources or Legal departments, where sensitive, confidential and private conversations are a daily occurrence. In these cases, we guide our clients using the Speech Privacy Potential, a metric used widely (including by the GSA) to gauge the level of voice privacy. It is the sum of the Noise Criteria of the room receiving the sound being transferred and the Sound Transmission Class of the partition.
The concept is that, if the person in the office next to you is talking loudly, there are two ways of limiting transmission of that sound: Either increase the noise level to cover up or mask what is being transmitted, or increase the performance of the wall or partition. The criteria is simply a way to express to the layperson what type of voice sounds will be heard and if normal voices will be audible or intelligible, and if that is typically acceptable for most office users.
For open work areas, the use of barriers is seldom an option. The requirements for daylight, views and openness often drives furniture and wall constructions to be limited in height and minimally used so enclosed or contained spaces are not created. The design tools at our disposal for an open office space primarily revolve around layout, acoustically absorptive surfaces and the use of sound masking systems.
Using Work Modes
In the early stages of design, the four work modes identified earlier are reviewed relative to the program of spaces. The compatibility of space is defined by the noise and activity associated with each operation, and the acoustical environment required for that space to function for its users. The most noise sensitive spaces are kept separated from the socializing spaces, while the collaborative are given ready access to the focused work areas. This grouping allows for efficient use of construction approaches, such that heavy drywall or upgraded partitions can be used in specific areas. Also, where HVAC requirements differ from a noise standpoint, these areas can be grouped to make most efficient use of quiet air conditioning systems where required, and more typical systems in the open where background noise is more beneficial.
Computer modeling of these approaches can aid the occupants to gauge the differences between the nuances of acoustical ceiling performance changes, small orientation changes (such as moving entrances) or reorienting spaces to face away from one another. The outcome-driven approach allows occupants to participate in the design discussion rather than be a recipient of it, and the use of visualization and naturalization tools enables clients to see and hear their space prior to construction, enabling clearer value decisions to be made.
Once the layout is most effectively designed, the acoustical absorptive surface areas are reviewed. In open and closed areas, the most effective use of absorption is the ceiling plane, not only because this is the largest surface area available and is close to all of the users, but also because this surface, if left untreated, is a key reflector of voice sounds in an open space. In many modern offices, where large expanses of ceiling tiles may not be the desired approach, the use of other treatments, such as hanging baffles, to both stop the reflections of sound and absorb sound, can be very effective. This, along with other tools, such as variations in ceiling height or spray-applied finishes, can assist in limiting the distance that sound carries throughout an office.
The other tool at our disposal is the use of a thoughtfully designed and carefully commissioned sound masking system. Commonly referred to as a “white noise system,” this grid of speakers can be above the ceiling, exposed or otherwise laid out in a space, with the intent of augmenting the background noise in sound level, sound spectrum and consistency or distribution of sound. A correctly designed masking system takes into account all of the geometry and planned activities of a space, including ceiling and plenum height, ceiling type, HVAC systems and their sound level and locations, daily telephone activity of occupants, density and spacing of people, etc. The spectrum is a fixed entity because this is what the occupants should hear, but the level of masking can be varied depending on the occupant’s activity and voice levels, and the even distribution of sound relates to speaker type, spacing and orientation.
Cerami’s recommended sound masking spectrum differs from a white noise spectrum in that the focus is on low frequency sound because this generates a perception of a more balanced sound for the users, which offers more comfort and uniformity. Sound masking can be used in many ways; in the modern workplace where the physical barriers of old are largely removed, this, along with acoustical absorption, is key to providing a comfortable space with meaningful acoustical privacy.
While common practice is to use sound masking in open work areas only, if designed with the necessary amount of control to allow for exact tuning of each space, sound masking can effectively augment the privacy of enclosed offices and conference rooms to limit what is heard in adjacent spaces or in the corridor. It can limit distractions for workspaces that may be adjacent to active corridors or spaces where layout dictates that pantry spaces might be near work areas. And they may be smart and adaptive enough to react to the changing conditions of the environment throughout the day or week.
Key Components for successful transition from one acoustical environment to another include:
- Understand and educate the client. We provide our clients with benchmarks and encourage them to tour similar spaces to gain a first-hand experience of how the environment sounds. We try to demystify the jargon and nomenclature of the specialists.
- Layout is key. When designing a space, use layout options to minimize possible conflicts in acoustical types as they relate to modes of work. Keep focused workers, e.g., accounting away from noisy spaces, such as pantries.
- Constructible solutions. Use suitable barrier construction for enclosed spaces, acoustical absorption in the ceilings and walls, and sound masking to augment privacy and limit distractions.
- Manage occupant expectations. Carefully explain the acoustical planning process used, the tools and construction implemented and, ideally, provide a mockup to facilitate a “kick the tires” experience with their new workplace.
Christopher J. Pollock, PE CTS, LEED AP BD+C is Partner at Cerami & Associates (www.ceramiassociates.com), a New York City-based acoustical, audiovisual and technology consultancy, with offices in Washington DC.