An assessment of the accuracy of a hybrid room acoustics model with surface diffusion facility

Computer modelling of acoustics in enclosures has developed into various forms, none of which have yet demonstrated 100% accuracy. This paper, therefore, details a study of room acoustic computer modelling that highlights weaknesses with existing modelling techniques. The study illustrates that for accurate prediction of many room acoustic parameters the modelling of surface reflections needs to be refined. Accounting for scattering in the modelling of all reflection orders would improve accuracy in the time domain and assist in the prediction of parameters such as reverberation time, early decay time and clarity index. Allowing the directivity of scattered energy to be modelled would improve spatial accuracy and prediction of lateral energy fraction. Definition of scattering parameters in the frequency domain would also improve predictive accuracy, especially at low frequencies, where geometrical modelling is particularly inappropriate. Improvements in accuracy may also be achieved by including the modelling of barrier edge-diffraction, especially for seating areas behind balcony fronts.