Understanding Sound Masking Devices: Enhancing Privacy and Productivity
Sound masking is the inclusion of generated sound (commonly, though inaccurately, referred to as "white noise" or "pink noise") into an environment to mask unwanted sound. It relies on auditory masking. Sound masking is not a form of active noise control (noise cancellation technique); however, it can reduce or eliminate the perception of sound. Sound masking 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 produced and published by Banneker (BBN) and Kavanaugh 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 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.
According to the International Facility Management Association (IFMA), maintaining consistent background sound levels is essential for speech privacy and occupant comfort. To create a consistent background noise that reduces distractions and improves speech privacy.
Adding noise to unwanted noise may seem counter-intuitive, but white noise provides a non-repetitious broad band sound.
Speech privacy and increased productivity by not be impacted by wandering sound as you perform your duties are two key benefits.
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.
With MyOffice, we’ll put together a sound masking plan for your office that offers superior sound control capabilities. It is a technology solution we use to achieve speech privacy for a specific area that is plagued by distraction and discomfort. This is done by adding neutral noise to the background so as to render the distracting noise powerless.
The good news is that privacy and comfort are not mutually exclusive.
You’ve heard of a smart phone? Well, this is the smart sound masking system in that it anticipates what changes need to be made and adjusts automatically. This system represents sound masking at its best in that it is highly effective all day. *The background noise emitted by the speakers will adapt based on the needs of the workplace, fluctuating higher and lower as is necessary.
Various organizations (ASTM, ASA/ANSI, GBI, LEED, ASHRAE, WELL, etc.) define unique categories for labeling acoustical zones with purpose and/or function.
Sound masking seeks to reduce the intelligibility of sound from a source by reducing the signal-to-noise ratio.
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.
Applications of Sound Masking
Sound masking can be applied in various environments to address specific acoustic challenges:
- 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. Sound masking is an effective solution in masking intruding noise.
Yes. Sound masking is one of the easiest acoustic systems to retrofit since speakers sit above the ceiling grid or on decorative mounts.
Types of Sound Masking Systems
The right outcome depends on three levers: the masking type (direct vs. diffuse), speaker layout/spacing, and smart zoning.
There are two primary types of sound masking systems:
Direct-Field Systems
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.
Direct-field sound masking uses downward-firing speakers for quick installs, but it often creates uneven coverage in larger offices. Direct-field systems work best in smaller offices or spaces with uniform ceilings.
Direct Field Sound Masking System
Diffuse-Field Systems
Diffuse-field systems, which send sound upward to the deck before reflecting it down, deliver more consistent results.
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.
Diffuse Field Sound Masking System
Classic (Analog) vs. Digital Sound Masking
Sound masking systems can also be categorized as classic (analog) or digital:
- A classic sound masking system is ideal for offices under 10,000 square feet because it’s simple, affordable, and field-tuned during setup. Analog is ideal for smaller offices under about 10,000 sq ft-it’s simple and cost-effective. Analog keeps hardware simple & labor light.
- 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. Networked control speeds commissioning & reconfiguration.
Key Considerations for Sound Masking System Design
Good sound masking system design keeps spacing consistent and tuning balanced. Great hardware can still flop with poor layout, missing zones, or no commissioning plan. In designing and implementing sound masking systems, several factors must be considered to ensure optimal performance:
- Good sound masking system design keeps analog layouts efficient-consistent spacing, clean zoning, and predictable coverage.
- Most offices perform best with roughly 15-16 feet between speakers, about 225 sq ft per unit. Keep on-center spacing near 15-16 ft even if the formula yields higher numbers; large floors benefit from tighter grids.
- Plenum installs keep hardware invisible while ACT diffuses sound evenly.
- Use closer spacing near reception or glass-heavy areas to avoid level dips.
- Leverage presets for departments with different noise profiles (sales vs. Over-spacing: Pushing beyond ~16 ft O.C.
If budgets are tight, spacing can stretch toward 1.7 × (2D + H − 4), but uniformity drops.
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.
| Feature | Direct Field | Diffuse Field |
|---|---|---|
| Speaker Placement | Downward-firing | Upward-firing (into plenum) |
| Coverage | Can be uneven in larger offices | More consistent |
| Ideal Environment | Smaller offices, uniform ceilings | Larger offices, varied ceiling heights |
| Installation | Quick installation | More complex installation |