Numerical modelling of the speech intelligibility in dining spaces

The objective of this paper is to study the basic characteristics of conversation intelligibility in dining spaces where the seat number and occupancy level are relatively high, and to investigate the effectiveness of strategic architectural acoustic treatments on improving the intelligibility. A radiosity-based computer model has been developed and a parametric study has been carried out using the model. Computation in a typical dining hall shows that a design merely based on the current guidelines for space use may lead to very poor conversation intelligibility. Increasing boundary absorption can typically increase the speech transmission index (STI) by 0.2-0.4. For a given amount of absorption, in a regularly-shaped dining hall the difference in intelligibility between various absorber arrangements is generally negligible, whereas in a flat or long dining hall it is important to strategically arrange the absorbers. The improvement in intelligibility by enlarging the area per diner, changing the ceiling height, and increasing the length/width ratio has also been investigated. For a given room condition, the model can give the maximum number of seats according to the requirement in intelligibility.