Semi-analytical prediction of energy-based acoustical parameters in proscenium theatres

Previous studies of the authors have shown that there are limitations when the existing acoustic energy models are applied to theatres. In the present study, a new semi-analytical model is developed based on site surveys and scale model measurements, aiming to overcome these limitations and provide a reliable prediction of the most relevant energy-based monaural parameters: clarity C₈₀, definition D₅₀, center time T_S, sound strength G, early strength G₈₀ and late strength G_L, in the stall of proscenium theatres for a comprehensive evaluation of the acoustic quality. Three full-size halls plus two scale model cases of another hall, which differ in dimension, acoustical condition and style of interior decoration, have been exploited as a sample for data analysis to propose the model, and another two halls not included in the sample are chosen for model validation. The results reveal that the proposed model has significant improvement in prediction accuracy than the existing theory initially developed for concert halls. The good agreement between the predicted values of the six energy-based acoustical parameters (i.e., G₈₀, G_L, G, C₈₀, D₅₀ and T_S) by the new model and those measured indicates that this model can be used for point-by-point predictions in the stall area of proscenium theatres with reasonable accuracy.