Understanding Office Sound Masking Systems: Enhancing Privacy and Reducing Distractions
Sound masking is the inclusion of generated sound into an environment to mask unwanted sound. Commonly, though inaccurately, this generated sound is referred to as "white noise" or "pink noise." It relies on auditory masking and is applied to an entire area to improve acoustical satisfaction, thus improving the acoustical privacy of the space. Sound masking means controlling background sounds in a developed environment.
It is significant and prioritizes modifying the background sound (in contrast to background noise). However, there is substantial evidence indicating that acoustical satisfaction within a space cannot be guaranteed without consideration of the three principal parameters of architectural acoustical design, formalized and established in the early 1900s by Sabine.
A sound masking system can be used to reduce the impression of intruding sound (reducing annoyance, distraction) and improve acoustic privacy (including speech privacy). Sound masking is an effective solution in masking intruding noise. Sound masking seeks to reduce the intelligibility of sound from a source by reducing the signal-to-noise ratio.
Sound masking is not a form of active noise control (noise cancellation technique); however, it can reduce or eliminate the perception of sound.
What is a sound masking system? In general, the purpose of a sound masking system is to provide for greater conversational privacy (and therefore improved productivity for those not involved in the conversation) in an open office environment by adding ambient noise and shaping the noise signal to mask speech. The noise signal is fed from a specially designed generator and amplifier to the sound masking (SM) speakers.
Typically, these speakers are positioned out of sight above ceiling tiles in plenum space, although speakers are sometimes used in open architecture truss type ceilings. Sound masking speakers, generators and amplifiers are typically sold separately.
Many people believe electronic sound masking systems cancel unwanted sounds but that’s not the case. Unlike technology used in some headphones (which cancels unwanted sounds in the confined space of an ear muff), that technology does not work on the scale of an open room. Instead electronic sound masking systems add ambient noise to an open area.
A specially filtered audio signal, described by the NC-40 Contour, increases ambient noise to effectively mask speech, making it more difficult to be understood.
What’s sound masking noise? Electronic sound masking systems are often called “white noise systems” or “pink noise systems” but neither term is technically correct. White noise (for audio use) is defined as “equal sound energy at each frequency over the usable audio spectrum.” Pink noise is defined as “equal sound energy per octave over the usable audio spectrum.”
By definition an octave is a doubling of frequency, so between 20Hz and 40Hz is an octave, between 40Hz and 80Hz is an octave, and so on. That means that compared to white noise, pink noise has much less energy in higher frequencies than it does at lower frequencies. Since human ears work in a logarithmic manner, pink noise sounds flat to the human ear, while white noise sounds overly bright.
In other words, because of the nature of human hearing, to us it sounds like pink noise has as much energy in low frequencies as high frequencies even though that is really not the case. A sound masking system doesn’t use white or pink noise but instead incorporates a very specific filtered noise (described by the NC-40 Contour) that has been proven scientifically to produce the maximum speech-masking effect.
What does SM noise sound like? Adding sound to a space actually makes the space seem quieter. It sounds counter-intuitive but it’s true. This is because the added sound reduces the intelligibility of human speech. Sound masking is an ambient sound, similar to the sound of airflow, that’s specifically engineered to the frequency of human speech you can target conversational distractions and make them less distracting.
Unlike white noise, sound masking is specifically engineered to match the frequencies of human speech and to sound comfortable, even pleasant, to the human ear.
The architecture and layout inside modern office buildings has changed considerably in just a couple of decades, going from numerous segregated rooms to an open plan style which allows for collaborative working and communication. This issue has become prevalent in a variety of places, from offices and call centres through to retail stores and high street banks.
The solution is to install Sound Masking, which is a dedicated audio system that adds an unobtrusive background sound to reduce the intelligibility of speech from adjacent colleagues or customers. It was created to address the lack of speech privacy in open office workstations. Sound Masking works by broadcasting white or pink noise through a speaker to reduce distractions or provide confidentiality.
The technology used in a Sound Masking system usually consists of a dedicated Sound Masking Generator which is a device that you install in the area you want to mask. Sound Masking is a highly effective way to stop people from being distracted by each other when making phone calls or having conversations within an open plan area.
Typically an office without Sound Masking will have an ambient sound level of under 40 decibels. An Ambient level is defined by the noise which occurs when nobody is present in the room. Conversational speech levels tend to be near 65 decibels causing conversations to be understood, and distracting to others, from up to 15 metres away.
In recent years a number of psychological studies have been undertaken in office environments to gauge the need and effect of Sound Masking. In one study it was found that there is a modest stress increase and diminished motivation caused by typical office noises, including speech.
In order for Sound Masking to work it must reduce the difference between the steady background level and the transient levels associated with both speech and other sounds. The system capabilities must also be determined based on the amount of people in the office. The main element which you have to consider is the size and placing of the speakers which will create the white/pink noise, as well as the Sound Masking Generator.
Various organizations (ASTM, ASA/ANSI, GBI, LEED, ASHRAE, WELL, etc.) define unique categories for labeling acoustical zones with purpose and/or function. Sound masking systems are often relied upon as a basis of design with Sound Transmission Class (STC, as supported by ASTM E336) or Noise Isolation Class (NIC, as supported by ASTM E336) to ensure an appropriate level of privacy between contiguous rooms.
Where is sound masking useful? Sound masking is useful in a variety of environments:
- Open office plans: Open offices can be either too quiet (where someone dropping a pen in the next cubicle is distracting) or too noisy (where the conversations of others in the office make it impossible to concentrate).
- Private offices: Private offices and other enclosed spaces often appear to provide privacy but do not. Many times, walls are lightweight and do not extend to the ceiling deck, but only to the ceiling tile. In these cases, sound can easily travel through partitions or over the walls.
- Public spaces: Sound masking is useful for reception areas, pharmacies, waiting rooms, and financial institutions. Sound masking is provided in the area where conversations should not be heard - not necessarily in the area where the conversation is taking place. For instance, a psychiatrist would not want those in the waiting room to overhear a private conversation with a patient, so sound masking is provided in the waiting area, but not in the psychiatrist's office.
Several cases exist where sound masking has been successfully installed for exterior applications, the most common target of concern being roadway noise. In one example application, a large artificial waterfall was constructed as part of the garden exterior of an urban hotel in Santa Rosa, California.
Plenum vs. Direct Field Sound Masking The plenum is the space between a "dropped" ceiling and the upper deck to the floor. In plenum sound masking systems, which employ a network of loudspeakers located completely within the plenum, were the first such systems developed and have been in use since the 1960s.
Plenum-based speakers typically range 4-10 inches (10-25 cm) in diameter and generally face upwards, towards the upper deck. This is done to reflect sound from the speakers to broaden, as much as possible, the footprint from the speaker in the work area. As with any commercial-grade sound masking system, an in-plenum sound masking system requires proper layout design, commissioning, and verification of the performance.
Disregarding the importance of any of these stages in implementation will result in a sound masking system that does not perform according to the specifications of an acoustician. Only the most sophisticated sound masking systems can control the background sound level and spectra of masking sound accurately and precisely throughout a space, made possible only with the smallest zones (spatial limits around a speaker) and sophisticated electronics and software.
Uniformity can be achieved by adjusting the acoustic output of individual or a small groups of speakers. Adjustments routinely include changes in the output volume and output spectra of individual speakers.
Direct field sound masking systems have been in use since the late 1990s. The name takes after the mechanics of sound transmission which considers the "direct sound path" from the loudspeaker emitted towards the recipients (listeners) underneath. Initially used as an accessory for open office cubicles, direct field systems have been fully integrated into at least one open office furniture system and have been designed to be installed both in dropped ceilings and in offices without any absorptive ceiling systems.
When installed in dropped ceilings, direct field systems use speakers that are mounted facing down. When a ceiling tile is not available, they are mounted facing down on any available structure, sending the masking noise directly into the intended space. Theoretically, a direct field system would benefit from speakers that are omnidirectional, meaning that they transmit energy equally in essentially all directions. However, direct field systems require tighter arrays of loudspeakers given the polarity of the emission of sound.
Key Considerations for Effective Sound Masking Sound masking isn’t just about dropping in a few speakers-it’s about building a consistent noise floor that improves speech privacy & focus. Poor design creates “hot spots,” uneven coverage, and wasted budget. The right outcome depends on three levers: the masking type (direct vs. diffuse), speaker layout/spacing, and smart zoning.
Direct vs. Direct-field sound masking uses downward-firing speakers for quick installs, but it often creates uneven coverage in larger offices. Diffuse-field systems, which send sound upward to the deck before reflecting it down, deliver more consistent results.
Classic (Analog) vs. A classic sound masking system is ideal for offices under 10,000 square feet because it’s simple, affordable, and field-tuned during setup. Digital sound masking, on the other hand, is built for larger projects - offering programmable zones, remote adjustments, and integration with paging or mass-notification systems.
Plenum installs keep hardware invisible while ACT diffuses sound evenly. If budgets are tight, spacing can stretch toward 1.7 × (2D + H − 4), but uniformity drops. Good sound masking system design keeps spacing consistent and tuning balanced.
Masking isn’t just an office play. Analog keeps hardware simple & labor light. Use closer spacing near reception or glass-heavy areas to avoid level dips. Good sound masking system design keeps analog layouts efficient-consistent spacing, clean zoning, and predictable coverage. Networked control speeds commissioning & reconfiguration.
Keep on-center spacing near 15-16 ft even if the formula yields higher numbers; large floors benefit from tighter grids. Leverage presets for departments with different noise profiles (sales vs. Over-spacing: Pushing beyond ~16 ft O.C. Great hardware can still flop with poor layout, missing zones, or no commissioning plan.
According to the International Facility Management Association (IFMA), maintaining consistent background sound levels is essential for speech privacy and occupant comfort. At Commercial Acoustics, our engineers develop sound masking layouts that balance coverage, cost, and comfort-complete with speaker counts, zoning recommendations, and stamped design documents.
To create a consistent background noise that reduces distractions and improves speech privacy. Direct-field systems work best in smaller offices or spaces with uniform ceilings. Analog is ideal for smaller offices under about 10,000 sq ft-it’s simple and cost-effective.
Most offices perform best with roughly 15-16 feet between speakers, about 225 sq ft per unit. Yes. Sound masking is one of the easiest acoustic systems to retrofit since speakers sit above the ceiling grid or on decorative mounts.
| Aspect | Considerations |
|---|---|
| Masking Type | Direct-field vs. Diffuse-field |
| System Type | Classic (Analog) vs. Digital |
| Speaker Spacing | Consistent spacing for balanced tuning |
| Zoning | Customized zones for different noise profiles |