When and Why to Employ Office Noise Reduction Strategies According to Acoustic Specialists
Good acoustics are important in any building, but in a commercial space, especially one that will be used for offices, noise is not only an issue of productivity, but functionality as well. Sometimes a workplace that is too quiet may also be problematic, potentially impacting employee privacy and productivity. It is about finding the perfect balance between “too noisy” and “too quiet.”
While office acoustics are often neglected in design because they are not tangible and cannot be "seen," it often makes an immediate impression on any occupant entering a space. If you have ever entered a conference space and had difficulty making out what the presenter was saying or have lowered your voice in an open office during a private conversation so as not to be overheard or to avoid disrupting your colleagues, then you have encountered poor acoustics.
At best these are minor disturbances but at worst, they negatively impact functionality, even making spaces outright unusable, and ultimately, can be the reason tenants leave looking for more functional environments. Acoustics is an important aspect of office design because, fundamentally, it can have a significant bearing on the way the space is used, occupant comfort, and tenant satisfaction.
Here are some important acoustical factors that you need to consider on when and how to leverage office noise reduction strategies in commercial buildings to realize not only a beautiful space, but a functional one too.
Sources of Noise in Commercial and Office Spaces
There are many sources of workplace noise, from equipment-generated noise, such as telephones, photocopiers, computers, and other office equipment, to occupant-generated noise, like people talking (on the phone or to each other), moving throughout the space (rolling chairs, sliding drawers), or playing videos.
Noise in office spaces can also be generated by building components, such as the background hum of a ventilation system, the squeak or slam of doors, or from external noise intrusion through the building façades. The choice of building materials can also impact the acoustics, creating a “noisy” environment. For example, an industrial designed space with concrete floors and walls and high ceilings will create an echo chamber effect where noise reverberates off the hard surfaces, exacerbating the levels of background noise.
Noise comes from many sources, but not all noise is created equal. Some background noise is acceptable, or even desirable, whereas others may be distracting. A steady, balanced, background noise can cover up office chatter, increasing speech privacy. However, variable, transient, or excessive noise can negatively impact our ability to hear others, especially at speaking events. The desirable acoustic environment depends on the intended use of the space.
When considering a traditional office environment, several acoustical factors need to be considered to effectively mitigate noise. The three primary acoustical considerations for an office space are:
- Background noise levels
- Speech privacy needs
- Reverberation control
Careful consideration of each area will lead to optimized office acoustics for a commercial building.
Understanding Background Noise in Workplaces
The level of background noise in an office can impact not only how the space is used but can also affect the functionality.
For instance, excessively noisy office environments can result in poor speech intelligibility, as well as difficulty concentrating, increased distraction, and therefore decreased productivity. Speech intelligibility refers to how well someone can be understood when speaking. If, for instance, a space is meant for hosting workshops and sessions, poor speech intelligibility due to excessive background noise can impact the functionality of that space.
Conversely, a workplace that is too quiet may also be problematic, as an excessively quiet environment can reduce speech privacy. Unlike speech intelligibility, in which background noise must be reduced, a speech privacy issue is a result of too little background noise. Consider the case of open offices, with their lack of dividers, or cubicle and open floorplans. When it is too quiet, occupants may feel uneasy because it can feel as if everything they say can be overheard by everyone else in the office.
With enclosed spaces like meeting rooms and boardrooms, excessively low background noise levels can reduce speech privacy between adjacent rooms. While a quiet environment in these enclosed spaces is conducive to speech intelligibility in meetings and via teleconferencing systems, it may warrant acoustical upgrading of the separating partitions to maintain the desired speech privacy.
Therefore, finding the balance between “too noisy” and “too quiet” is essential. The ultimate goal is to prevent unwanted noise, while ensuring there is enough noise to optimize the functionality of the space.
How to Reduce Background Office Noise
Reducing background noise will depend on whether the noise is too excessive or too quiet. To prevent background office noise levels from getting too loud:
- Ensure that building services (mechanical, electrical, and plumbing) have had adequate acoustic treatment applied (ideally determined during the design development phase of an office fit-out)
- Verify that the building façade (e.g., glazing and walls) has adequate sound insulation performance to block noise intrusion from the outside (ideally determined during the design development of the building).
- Locate main ducts, fan coil units, and and other HVAC systems above corridors (which are less noise-sensitive and where masking noise is more useful)
- Select diffusers with appropriate noise ratings for the spaces they serve
If noise levels are too high in an existing office because of building services noise, it can be difficult and costly to retrofit acoustic treatment. It is best to have these issues resolved and accounted for during the design stage.
If background noise levels will be too low in an office environment, the following could be implemented:
- Use sound masking systems with a balanced spectrum so that it does not sound unnatural and draws attention to itself. Review the design of the building services to check there is no unnecessary excessive acoustic treatment.
- Adjust the mechanical services to generate noise if spaces are too quiet.
How Office Acoustics Can Improve Speech Privacy
Speech privacy can be critical in some office settings where the contents of confidential conversations must not be heard in neighboring rooms. Government offices, financial institutions, or healthcare offices are just some examples where privacy may be of concern.
In the case of enclosed spaces, like meeting rooms and boardrooms, speech privacy is achieved through suitable constructions for the room partitions. These are usually the walls but can also include the floors and ceiling. The higher the level of speech privacy required, the heavier and thicker the wall construction will need to be.
Another key consideration for wall constructions is potential acoustic weaknesses, or flanking paths, that may be present or introduced into the wall. Flanking paths are noise paths, typically gaps or cracks around the edges of internal walls or around building elements that allow sound to flow through them. This can include elements like doors or glazing, penetrations for building services (e.g., ductwork or cables), power points, and openings above the finished ceiling, such as when walls are not full-height (i.e., slab-to-slab). All potential flanking paths need to be considered and addressed or the acoustic separation between two spaces can be undermined and will not provide the desired acoustic privacy.
Addressing existing speech privacy issues between meeting rooms or private offices is also typically difficult and costly. Ideally these flanking paths should be addressed in the construction detail drawings at the design development phase of a fit-out.
Speech privacy can also be improved by increasing the background noise levels in the two spaces, however there are limitations to this approach because at some point the background noise levels will become too noisy.
Why You Also Need to Consider Reverberation
Part of what makes background noise disruptive in an office is the reverberation it can cause. Reverberation is essentially an echoing sound. Reverberation time refers to how long it takes for sound to dissipate in a room and is governed primarily by the size of a room and the ratio of hard, reflective surface finishes to soft, sound absorbing finishes. The more sound-absorptive finishes a space has, the shorter the reverberation time will be.
Controlling reverberation within spaces like meeting rooms is critical for speech intelligibility, especially for rooms where teleconferencing occurs, or spaces used for conferences and presentations. Excessive reverberation in these types of spaces can greatly degrade speech intelligibility, where it is difficult to hear or understand a speaker and can even render some teleconferencing spaces unusable.
Consider a large, open concept workspace with high ceilings, concrete floors and walls, and hard surfaces throughout. This workspace can experience excessively long reverberation times leading to the buildup of high levels of reverberant noise, which can make these spaces uncomfortably noisy, especially when many people are talking. Just imagine how loud it can become in a busy restaurant and how difficult it can be to have a conversation when the space is very reverberant. This is similar to what can happen in a workspace that has poor reverberation control.
Reverberation is primarily controlled through the installation of sound absorptive finishes in appropriate locations within a given space. Think of the amount of carpet in office spaces or the padding office dividers. Sometimes, creative furniture that is made from sound absorptive materials can be used to add soft finishes to a space as well.
As always, it is preferable to incorporate sound absorptive materials as part of the design process since doing things retroactively or once the building is built can be costly. In many cases, it is possible to retrofit absorptive finishes to an existing space that has reverberation issues, and there are acoustic finish products available to suit almost any desired aesthetic. However, there can be additional labor costs associated with retrofitting acoustic treatments, not to mention the disruption caused to an already occupied space.
Examining the acoustics of a commercial building, especially one that will be used for office space, is critical in establishing a functional environment that potential tenants will see value in. Reducing background office noise is important, but so too is ensuring that some noise is present in order to preserve privacy.
While there is no one-size-fits-all approach, what does matter in ensuring high quality acoustics for building occupants is that these considerations be made early in the design process in order to prevent costly issues down the road. Good early acoustical design is the best way to balance these competing factors and ensure the space meets its intended goals.