Should we just accept that it takes 20 metres for the sound level of someone’s voice to drop to a comfortable non-distracting level, or should we reduce this to 10 metres so that workgroup-to-workgroup distractions are minimized?
In the Nordic Innovation report “Acoustic design of open-plan offices” , it was found that in a Swedish call centre, when reducing the distance for the sound to drop from 60 to 40 dBA from more than 16m before acoustic refurbishment to less than 4m thereafter, the proportion of people rating their acoustical environment as “bad” was reduced from 40% to 10%, and the proportion rating it as “good” increased from 20% to 60%.
This report is also referenced in the ISO3382-3:2012 “Acoustics — Measurement of room acoustic parameters — Part 3: Open plan offices”, which explains how to measure acoustically in an open space office.
The standard includes a recommendation saying that the distance for an average voice (~57dBA) to drop to 48dB should be around 4m. This correlates to our subjective experience of hearing the voice half as loud, so in laymen terms this means that in a good office, a voice should be half as loud at 4m distance from it. This is however, rarely the case, which can create an acoustical challenge in the office, not only in terms of comfort, but also in terms of stress, performance, job satisfaction etc.
As open spaces become more and more common and activity based design increases, the acoustical challenge increases. It becomes more and more important to think of the resulting acoustics as a total solution, meaning building + workplace design + furniture + activity etc. But perhaps more importantly, the need to understand and use available acoustical standards as the ISO3382-3:2012 increases, as well. Luckely, it now seems that the leading acoustical simulation softwares have incorporated this standard into their softwares.
A round table session regarding this topics called “Enhace your workplace with activity based acoustic design” will be held at the EFMC2013 in Prague May 24-25th.