Empirical method for predicting speech sound propagation in offices

The room acoustic parameters of ISO 3382-3 allow for an evaluation of sound propagation and speech intelligibility in open-plan offices and have increasingly been used in the planning process since their introduction in 2012. The input parameters are the speech sound pressure levels and the speech transmission indices at the workstations along a measurement path including a sound source (imaginary speaker). ISO 3382-3 is a measurement standard - a calculation method is not defined. However, it is possible to calculate the necessary input data, namely the speech sound pressure levels and the speech transmission indices, using room acoustic computer simulations. Although computing power is no longer a limiting factor today, the modeling and verification of computer models are still complex and correspondingly time and cost intensive. Hongisto and Keränen (2013, 2015) describe a model for predicting the ISO 3382-3 parameters. In this study, this prediction model was tested using measurement data from several open-plan offices in Germany. Recommendations for the application of the model are derived from preliminary investigations, and the limitations and boundaries of the method are further specified.