Sound masking systems, sound-absorbing ceiling tiles and panels, and enclosed pods are just some of the ways designers have attempted to combat the high levels of noise that plague open-plan workspaces.

For their part, employees have resorted to wearing headphones or using white noise machines to block out unwanted ambient sound. None of these strategies have proven to be wholly effective. New technologies, however, may offer a more satisfactory solution.

Recently, researchers at the University of Sydney announced they have had some success isolating employees from noise using a new type of sound management material.

Instead of masking, absorbing or dispersing the sound waves created by office activity and machinery, as current products do, this material uses the properties of faceted geometries to reflect the sound back to its source.

On the face of it, this may seem counterintuitive. Wouldn’t bouncing the sound back create additional noise?

The researchers explain that "retroreflection," as they call it, produces two desirable results. First, it reduces the amount of conversation or other sound that can escape into the surrounding area by localizing it to the speaker.

Second, previous acoustic research has shown that hearing one’s own voice at a comfortable level when one is speaking both mitigates one’s awareness of background noise and induces one to lower one’s voice level.

Think of a time you were in a closed space with a lot of ambient noise and many other people engaged in boisterous conversation, such as in a restaurant, bar or reception. Even though you may be standing close to the person you are speaking with, the louder the noise in the room, the more you are inclined to raise your voice in order to be heard.

The ambient noise causes you to perceive your voice level as being softer than it actually is. Retroreflection counteracts that tendency by reinforcing the sound of your own voice. It works both physically and psychologically.

Among all the types of annoying noise commonly cited by employees in open-plan spaces, speech distraction caused by other workers’ conversations and phone calls tops the list. It is highly disruptive to concentration and cognition, and has been shown to raise stress levels and reduce productivity.

Retroreflective materials have the potential to greatly reduce the amount of speech distraction in an open environment.

In another study, Manuj Yadav, a postdoctoral research associate at the University of Sydney, and colleagues combined the use of retroreflective ceiling material with high-backed, egg-shaped chairs to create "acoustical islands" in a laboratory setting designed to simulate an open-plan environment.

The shape of the chairs helps to block out ambient noise, explains Yadav, while the retroreflective ceiling "allows you to hear your own voice reflected back to your ears much louder than is possible with flat or other types of hard ceiling surfaces or absorptive ceilings."

The net effect is that one is able to hear one’s own speech clearer while that of others in the area is diminished.

Yadav acknowledges that the findings up to now have been based on laboratory experiments and that more research needs to be done with occupants in actual open space environments. Still, these early studies show, he says, that the local acoustic treatment employed "can, in many cases, provide substantial enhancement for speech communication at short distances and reduce the disturbance due to ambient noise when you're trying to concentrate."