Ecophon Acoustic Bulletin

The conclusions presented by the chairmen to the reporting committee are:

Open offices

- Reduction of work performance due to speech noise can be predicted by the STI value (speech transmission index) between two positions in the open plan office.

- Acoustic quality of open offices may be determined objectively by measuring the spatial decay of STI and speech sound level at a given point. These represent better subjective assessment of the room conditions than temporal decay, i.e. reverberation.

- Reverberation time should not be used as a primary descriptor of acoustic quality in open offices. Instead, specific descriptors like DL2 and Radius of Distraction should be considered. Also, target levels specifying the acoustic relationship between workstation clusters were presented.

- Standardisation of measurement methods should be started as well as establishment of European recommendations for acoustic target levels.

- Room acoustic noise control is a very efficient way to improve sound environment and requires a simultaneous control of high room absorption, appropriate background noise level and appropriate screening.

- An open plan office acoustic design tool is freely available on the internet. Address is

- A holistic view is needed when it comes to open office ergonomics, where acoustics is a part of office design. Nevertheless there are at this date enough approaches, methods and solutions to start improving the acoustic quality as such.

Call centres

- Noise level can exceed 85 dB in ear canal because of poor quality or misuse of headsets. Special concerns should be paid to the choice of headsets and education of the operators.

- Room acoustic design of call centres can be basically conducted like in ordinary open offices, but extra emphasis should be put to the local absorption inside the workstations (“acoustic bubble”)

- Sound levels in computer data centre rooms (server room) can exceed 85 dB because of increased need of cooling.

- Despite of call centre specificities regarding activities and workflow, there seems to be little reasons to separate call centre acoustics from regular open plan office acoustics.

Pierre Chigot, Ecophon, France
Valtteri Hongisto, Finnish Institute of Occupational Health, Finland
Chairmen Open Plan Office Acoustics and Call Centre Acoustics
Lille 5 July 2007