Prediction of acoustical parameters for open plan offices according to ISO 3382-3

In the new international standard ISO 3382-3 the measurement procedure for open plan offices is described and a number of new room acoustical parameters for the objective evaluation are defined. Among the new parameters are the privacy distance and the distraction distance, both derived from the STI (speech transmission index) as a function of distance from the sound source. The final evaluation is a balanced compromise between a number of parameters that depend on the amount of sound absorption, the application of screens between work stations and the level of background noise. With room acoustic simulation software these measurements can be simulated, thus providing a tool for the acoustical design of open plan offices. The paper presents an example office with a range of alternative acoustical solutions that include different amount of absorption, screens of different height, and different levels of background noise. Also the influence of dynamic background noise from people talking can be taken into account, leading to a shorter privacy distance. This provides a background for the discussion of the efficiency of various acoustical measures in open plan office design.