Experimental Verification Of Acoustical Radiosity Model In Enclosures Of Diffusely Reflecting Interfaces

The acoustical radiosity method is a theoretical model based on geometrical acoustics to predict sound fields in enclosures assuming purely diffusely reflecting interfaces.In this paper,two enclosures with highly diffusely reflecting interfaces are designed.Sound source and several measuring points are arranged in enclosures,then the impulse responses are measured.The distribution of some acoustical parameters are obtained by calculation,including relative sound pressure level SPL,relative reverberation sound pressure level SPLr and ratio of reflected sound energy to direct sound energy C.The absorption coefficients of reflecting interfaces compatible to different simulation methods were estimated by adjusting absorption coefficients to make the sound decay rates in experiments and simulations are closed.Besides acoustical radiosity model,the simulations of image source model and classical theory model are carried out for comparison.Comparing the acoustical parameters obtained by experiments and simulations,the results show that the acoustical parameters in experiments are discrete when the frequency is low.The acoustical parameters simulated by acoustical radiosity model are not easy to match with them in experiments,but the performance of acoustical radiosity model is better than the other two models.When it is above a certain frequency,which is 5 kHz in one enclosure and 6.3 kHz in another enclosure,the simulation values of acoustical radiosity model begin to show good compatibility with the measured values.When the frequency bands ideally have diffusely reflecting characteristics,the acoustical radiosity model can accurately simulate values of the relative sound pressure level SPL and the relative reverberation sound pressure level SPLr.