A major company has just completed the refurbishment of 5 floors of the their office on George Street, Sydney and while embracing the latest in Activity Based Working (ABW) Savills in conjunction with Acoustic Studio have also introduced an ‘unseen’ but nevertheless essential addition to the fit-out which allows ABW to perform optimally.
As sedentary working gives way to more flexible collaborative activity it is increasingly difficult to separate office noise from quiet focus. As ABW and the interior space planning and design that accompany it, promote activity and shared space, sound conditioning is now the key to its success.
In simple terms there are 2 undesirable sound scenarios for commercial workspace:
1. Too Loud 2. Too Quiet
1. ‘Too Loud’ makes obvious sense. This is usually due to high levels of activity in an interior space without adequate absorption (i.e. the sound produced by the activity bounces around and has nowhere to go. It builds up as people compete to be heard). An everyday example is the trendy minimal restaurant or bar with concrete floor smooth walls and shiny furniture. As the place fills up you can barely hear the person right next to you. Sound builds up to what can be dangerous levels increasing stress and fatigue.
Remedy: Absorbent surfaces: acoustic ceilings, absorbent panelling, and soft furniture and so on – the list of products now on the market is endless.
The effect of applying the absorbency is to reduce the reverberation and overall sound level. In the case of a busy restaurant or bar its job done (if applied properly, that is) However, in an office the sound of activity is much more random and sporadic and simply applying absorbency will stop the reverberation but render the space too quiet.
2. ‘Too quiet’ makes less sense to many. The key here is background or ambient sound. Traditionally, ambient sound in office space is usually supplied by air conditioning and computer fans etc – it’s the sound which is in the space 100% of the time as opposed to the random sounds of human activity. In most good quality office space absorption levels are high due to the use of acoustic ceilings and carpets etc. However, modern air conditioning systems no longer contribute enough sound and those that do, deliver it very unevenly. Eco friendly chilled beams are almost silent. When someone speaks (even in a whisper) in a quiet office environment, it is loud against the low ambient sound level. Conversation between workers is random and very distracting to those in quiet focus.
Remedy: Adaptive Sound Conditioning. This is the latest evolution of sound masking or white noise. An artificial sound designed to sound like air conditioning is produced through speakers hidden above the suspended ceiling tiles. The sound is carefully introduced into workplace below providing optimal sound levels as activity increases and decreases.
[Optimal sound levels are 35-40dB in cellular and 40-45dB in open-plan set by Australian Standard 2107:2000. Greenstar points are awarded for achieving these levels and consequent acoustic comfort. Most modern interior workspace fails to comply with these standards and as a result their performance is greatly impaired] [White noise, pink noise or standard soundmasking systems have been around for a long time and if carefully installed can work well, however, often fail in the modern workplace designed to encourage interaction between workers at any time and any location over a large open and semi-open plan environment. As some areas become quiet as collaboration is replaced by solo work the masking sound remains the same and is unnecessarily loud and becomes annoying. When activity picks up the masking becomes less effective at masking that acoustic activity from the solo workers. Acoustic Engineers – SoftdB’s adaptive sound conditioning system uses sensors in the ceiling to monitor activity across the entire workspace adjusting the masking level automatically throughout the day as activity increases and decreases conditioning the soundscape for optimal productivity
Without sound conditioning, however, things would be quite different. The necessary measures taken to absorb sound in the space to prevent unnecessary build up simply render the workplace overly quiet. This is when an office is at its least productive. When ambient sound is at such a low level the slightest sound is very distracting. Oddly, often the complaints about this kind of environment are that it is too loud! This is because, against the quietness, the sound of normal activity seems loud. In this workplace, not only to workers hear everything, they hear too much of everything and this is the real problem – it’s not just the sound of others talking, it’s the high level of detail or intelligibility of that conversation which draws their attention away from their solo focused activity. No matter how dull the conversation’s content, we humans just can’t stop ourselves from tuning in!
This is where productivity really suffers. If you imagine being ‘in the zone’, really focused on hitting that deadline and you are interrupted. It will take you at least 5 but usually 10+ minutes to get back to where you were. Then consider how often these interruptions actually happen – probably a 3-4 times an hour (if you’re lucky). That’s a lot of wasted time – say a minimum of 15-20mins of every hour. Not only that, but constant interruption is stressful. Ever wondered why you feel so stressed and tired at the end of the day with disappointingly little to show for it?
This has always been a big problem with open-plan, however, when ambient sound is too low it affects the entire fit-out.
In cellular offices and meeting rooms, partition walls must be robustly (and expensively) built in order to render speech unintelligible. Furthermore, out of sight above the acoustic ceiling tiles, large amounts of densely packed acoustic insulation must be installed to stop speech flowing over the top.
Acoustic Consultants, AECOM, recently tested the effect of low ambient sound on partition walls as below:
If you consider a room where the background noise level
is circa NR30 the sound insulation performance of the
partition between two adjacent spaces would need to be a
minimum of DnTw 40dB in order to achieve a ‘good’ level of
privacy (follow blue line). If however, the ambient /
background noise in the room receiving the noise was
increased to for example NR40 the sound insulation
required to achieve an equivalent level of privacy would
reduce to DnTw 30dB (follow burgundy line).
So, if you take control of ambient sound level and install sound conditioning at the base building stage you don’t have to work so hard on those partition walls. In fact, if a good quality ceiling tile is used (NRC 0.9 and CAC 40 – see Rockfon’s Sonar dB 40) the partition wall performance can actually be reduced to less than 35Rw and achieve the desired decrease in speech intelligibility. If you’re hoping for absolute silence between partitioned rooms, fit-out costs will go way higher than your partitions!
So, accepting that unintelligible is the aim, why not get your ambient sound level up to where it should be using sound conditioning and enjoy the benefits of a lower rated (35Rw) wall in conjunction with the Rockfon (or similar) tile and negate the need for any (yes, none) insulation in the plenum? Great news too is that 35Rw opens the door (sorry) to the flexibility of demountable partitioning which achieve the level of fit-out flexibility needed for the ongoing requirements of modern businesses.
So, how does this affect the workers?
They have ample absorption in the workplace thanks to the use of a high quality ceiling tile throughout. This is further assisted by breaking up the space with small closed meeting rooms and breakout furniture with high backs which capture and block much of the sound made by and received by the user.
The more natural, organic furniture layout also serves well to disperse speech around the office.
In the open-plan workers – unaware of the sound conditioning – experience:
1. Acoustic Comfort: Subconsciously aware that they cannot hear the detail of their colleagues’ conversation (although able to hear the sound of it) they relax in the knowledge that they can have their own discussion either with colleagues or on the phone etc. without distracting others. Ever found yourself automatically lowering your voice when on the phone or in discussion in the open-plan? That’s a sure sign that it’s too quiet.
2. Enhanced Speech Privacy: Even though they’re working for the same business they would much rather their colleagues didn’t judge their every word. With sound conditioning working at the correct level they can talk freely in an acoustic bubble only fully intelligible to their close team mates. For those conversations that others must not hear, they can retreat into a breakout room which is confidential.
3. Increased Productivity: Although still interrupted from time to time directly and deliberately by colleagues who require their input, they are able to really find focus when they need to as their concentration is not so easily diverted by other conversation not requiring their input.
Instead of the sleepy library like environment endured by so many, they enjoy a dynamic, productive workplace which encourages the collaboration and knowledge sharing they require.
As the demands and working culture of modern business changes, traditional acoustic product and labour intensive fit-out is fast becoming irrelevant. Hardy Sound Management work with Australia’s leading consultants to build cost effective, acoustically optimal fit-out solutions tailored to your building and business needs while meeting the design and acoustic performance required to attain Greenstar credits.