Commonwealth

The age old acoustic problem of the open-plan office layout is that some activity is quiet and requires concentration while other activity is collaborative and hence noisier. Therefore, sadly, the worker who needs to get to a deadline and really focus on an individual task finds it difficult to concentrate.

Both of these buildings use a new type of environmentally preferable and efficient air conditioning known as chilled beams. Unlike traditional HVAC systems these make almost no sound. Great! you might think – unfortunately not.

When it comes to concentration on a focused task, quietness punctuated by random sounds is a killer. Remember when you were last in a quiet library deep in your research when someone came in at the other end of the library and had a normal conversation with the librarian? Your concentration was instantly lost as your brain locked into their conversation. You couldn’t help it – the words “can you tell me where the loos are please?” were just too much to ignore!

The problem here is that the background or ambient sound level was too low and as a result speech intelligibility was dramatically increased.

In a building with chilled beams, or rather, without the humming fan sounds of traditional HVAC, ambient sound level is very low which create very quiet workplaces. The answer to this problem is to artificially increase the ambient sound level and this is done using a familiar unobtrusive sound which sounds like air conditioning.

White Noise, Sound Masking and Sound Conditioning

The theory behind sound masking or using an unobtrusive sound to increase ambient sound level has been around since the 50′s. White Noise was a simple, but rather crude sound (high in higher frequency hiss) which was delivered through speakers in the ceiling. Unfortunately, the distribution of the speakers (too far apart creating ‘pools’ of sound) and the sound itself soon became an irritant to the worker and thus defeated their purpose. About 15 years ago Sound Masking was developed thanks to advances in digital electronics. This was a purpose built system consisting of sound generator and specially designed speakers. The sound was manipulated to minimize those high end ‘hissing’ frequencies and the speakers were placed never more than 5m apart. This generation of the technology has been successfully installed throughout the world, but still can be a problem if the sound is not delivered at the correct level. The latest, 3rd generation of this technology is called Adaptive Sound Masking or Sound Conditioning. As air conditioning delivers an optimum temperature into a space no matter what the temperature outside, manufacturer SoftdB’s masking system actually listens to the activity level in the space and automatically adjusts the sound level to maintain an optimum ‘soundscape’ no matter what the activity level – very clever!

In the open-plan office low ambient sound level directly impacts on the productivity and comfort of the occupants. As a worker attempts to concentrate on their current individual task to hit a deadline, their colleagues’ break-out into collaborative discussion, and they are interrupted. The problem is not the noise ‘level’ it’s the ‘content’ of the conversation. Their brain immediately locks into the words and wants to know more. After the interruption it takes them 5-10 minutes (at least) to get into that focused zone only to be interrupted again and again. In many circumstances workers will struggle to get anything done all day and stress levels will have increased accordingly. If you consider a conservative interruption rate of 4 per hour you can see how productivity takes a nose dive.

The new ‘physical’ attributes of the the new Sydney offices – Macquarie’s garden, playroom, cafe and plazas etc certainly help solve this problem, but it’s the sound masking that really makes it work.

Macquarie

Open plan with cellular acoustics

Sound masking lets you have your cake and eat it.

By increasing the ambient sound level in this way the open-plan changes from an exposed work house into an ‘invisibly cellular’ environment. You can converse with your colleagues normally at close proximity (up to 3-4m) but further away you can see others in collaborative mode but you can’t hear enough detail in the conversation for it to be distracting. Conversely, when you need to collaborate with your team you don’t feel inhibited either by others overhearing the detail of your conversation or by you interrupting them.

Having described the benefits of this technology in the open-plan, there are considerable benefits for the wider interior fit-out. Please post comments below or on LinkedIn below the discussion – the feedback would be really appreciated.

Until my next post…

Tom