I've already mentioned a few times that effective interior acoustic design is achieved through a combination of strategies, including physical barriers, absorption and sound masking. Each of these contributes differently to the overall performance of your space.
But one aspect I haven’t covered is which design elements affect noises and conversations occurring close to you and which ones have a greater affect over distance. All three strategies contribute to the overall acoustic experience in each local area, but some methods have a stronger impact over shorter distances, while others are more effective over longer ones.
Sound masking certainly affects the ambient sound levels in each person’s local area, but it won’t impede conversation in their immediate vicinity. Voices and noises must be below the level of the masking to be completely covered and this only tends to happen after the voice or noise has traveled some distance and reduced in volume. This is a good thing, because otherwise you wouldn’t be able to talk to people in your office or workstation. However, it also means that you’ll be able to hear nearby conversations if the acoustics in your space aren’t properly addressed using other means.
Absorption won’t control noise and conversation over short distances either. Why? Because in order for the absorptive material to have an effect, a sound has to reflect off of its surface. Other than when a person’s voice reflects off an absorptive partition in front of them, this doesn’t tend to happen to conversations occurring nearby because the key pathway for the sound is a direct one (particularly if there isn’t a physical barrier between the speaker and the listener).
The only way to quickly reduce the volume of sound over a short distance is via physical blocking (for example, using walls or workstation panels). If this component is missing, the other design elements can help to reduce overall volume levels and deal with noises from farther away, but local noise sources will remain intelligible and disruptive.
This problem is on the rise due to ever-dropping partition heights and greater use of open space. Green building, desking and benching trends are seeing the near elimination of physical separation between occupants. At the same time, increasing densities mean more and more people are working closer together.
The bottom line is that physical separation of nearby occupants is an essential element of acoustical design. Without it, you can’t achieve noise control and speech privacy over short distances. This isn’t a new message, but one that merits repeating in light of these current trends.
Next week...how tall does a workstation partition need to be to provide acoustical benefits?