Select a System

Making an informed decision about sound masking can be challenging, but it’s worth the effort.

A well-built sound masking solution typically has a long lifespan, which means you’ll need to plan ahead to ensure optimum sound quality and adjustability as your needs change over the years. Without some prep work, your system may not provide the acoustic control you want—meaning that unless you do your homework, you may regret it later.

The best way to choose the right sound masking system for your needs is to focus on the six qualities that are critical to comfort, effectiveness and flexibility.

Select a System

Adjustment zone size

Zone size is the single most important factor in ensuring your sound masking system works well.

Why? Acoustic conditions and user needs vary between private offices, meeting rooms, corridors and reception areas, as well as across open plans. By their very nature, sound masking designs that use large adjustment zones (e.g. involving more than a few loudspeakers) will need you to make compromises.

For example, if the sound masking volume needs to be raised to improve the system’s effectiveness in one area, it might be too loud in another, affecting occupant comfort. Choices made for comfort may in turn affect speech privacy.

Less truly is more: using one to three loudspeakers in each zone (i.e. 225 to 675 ft2) provides a high degree of control and flexibility, enabling you to more easily adjust volume and frequency as needed.

Masking sound generation

Each adjustment zone should feature its own masking sound generator in order to avoid a phenomenon called “phasing,” or uncontrollable variations in sound masking levels.

And to make the sound as unobtrusive as possible, each generator should provide a sound that occupants perceive as random (i.e. with no noticeable repeat cycle). If there is no noticeable loop, and the masking can also be finely tuned to suit the needs found throughout the space, occupants do not focus on the sound.

The sound produced by the generator should cover the entire masking spectrum, which is typically 100 to 5000 Hz, or as high as 10,000 Hz.

Volume adjustment

Your facility’s interior will impact the masking sound regardless of how the sound masking loudspeakers are installed (upward-facing or downward-facing, sometimes called ‘direct field’).

If zones are too large, many loudspeakers will be set to the same volume setting, but the sound masking volume will fluctuate as it interacts with workplace design elements, furnishings and other materials.

Some large-zoned designs try to mitigate this problem by providing audio transformers on each loudspeaker; however, these only offer coarse adjustments in 3 dBA steps.

Unless you can finely adjust volume in small areas, you’ll need to settle for an “average” level. That’s good for no one, as it compromises comfort and effectiveness at unpredictable points across your space.

How much? You can typically expect a 10% reduction in performance for each decibel below the target masking volume. Oddly though, a poorly designed system will allow for as much as 4 to 6 dBA variation. This will cut your system’s effectiveness in some areas by 50%. Your system’s performance will be further reduced if it must be tuned to a lower overall volume in order to avoid exceeding the typically recommended maximum of 48 dBA in some areas.

These peaks and troughs call occupants’ attention to the sound as they move through the space.

Frequency adjustment

Your sound masking system should provide fine frequency control for each small adjustment zone. The range of masking sound is generally specified to be between 100 to 5,000 Hz, or as high as 10,000 Hz. The system should provide control over these frequencies via third-octave adjustment—which is both the industry standard, and the basis for masking targets set by acousticians.

Loudspeaker requirements

As long as your sound masking system can meet the volume and frequency targets established by your specification, there’s no need to specify the loudspeaker’s size, wattage rating or other parameters.

That said, very small drivers (less than 3 inches or 76mm) are unlikely to generate sound down to 100 Hz, the minimum frequency necessary to create the full masking spectrum. These lower frequencies play a relatively small role in reducing speech intelligibility, but they are vital to occupant comfort.

Look for masking loudspeaker drivers between 4 and 8 inches (102 to 203 mm) in diameter, and rated from 10 to 25 watts.

Measured results

You can’t truly know whether your sound masking system is performing as you want it to until you measure after it’s installed and tuned.

Make sure your vendor or acoustician tests in 1000 ft2 (93 m2) open-plan area and each closed room, and have your vendor adjust the sound masking system within that area as needs dictate.

Note that some providers may outperform this requirement, but it is a good baseline.

To ensure comfort and dependable performance across your space, overall volume should be consistent within a range of 1 dBA (±0.5 dBA) or less. The volume of each third-octave frequency should meet the specified level as closely as possible. You can specify ±2 dB within each band, but note that this is the maximum allowable deviation and should only occur within a few bands, not as a rule.

With these six factors forming the basis of your choice, feel free to add any other requirements you see fit—for example, the appearance of the loudspeakers in an open ceiling, UL 2043 compliance, and so on.

Additional considerations can include: control methods; zoning methods; timer functions; paging and music functions; security features; certifications; installation versatility; scalability; and appearance.