CFM&D magazine recently asked me how often a sound masking system’s performance needs to be measured to ensure it’s operating at target volume.
It’s an excellent question and one that I was only too happy to answer, knowing that some providers promote a ‘set it and forget it’ approach, while others claim there’s no need to adjust the system at all.
A masking sound is affected by the overall workplace design, including the materials used, furnishings, and location on the floor. These elements have an impact no matter how the loudspeakers are installed (upward-facing above a suspended ceiling or direct-facing cut through a ceiling). For this reason, ASTM E 1573-09, Standard Test Method for Evaluating Masking Sound in Open Offices Using A-weighted and One-third Octave Band Sound Pressure Levels, requires measurements to be taken in areas representative of all workspace types.
The likelihood of making changes to the physical characteristics of your space (e.g. furnishings or partitions) and to occupancy (e.g. relocating departments) is almost certain over the course of your masking system’s 10 to 20-year life span. If adjustments aren’t made afterwards, the overall volume might be too low in some areas, affecting speech privacy and noise control, and too high in others, affecting comfort. In fact, you can usually expect a 10% reduction in performance for each decibel the masking sound falls below target.
Spectrum variations can also mean substantial losses in speech privacy and noise control, so it will be necessary to adjust frequencies too. You might also need to revisit paging or background music zones and levels, if you use these functions.
The great thing is that developments in masking technology have removed the system itself from the maintenance equation (older analog masking systems needed to be checked periodically, whereas the output of modern digital systems is consistent over time) and also made it both faster and easier to make the required changes (from a central control panel or software). As long as your masking system provides fine control over small adjustment zones (0.5 dBA increments for volume; third-octave control over the entire masking spectrum of 100 to 8000 Hz; zones of 1 to 3 loudspeakers), you’re well positioned to ensure the highest levels of performance over time.
So, when you make changes to your space, contact your rep and they can ensure your sound masking system’s still performing at peak levels. After all, when you invest in this type of technology, it’s not simply for the pleasure of owning the equipment!