Diffuse Reverberation Model for Efficient Image-Source Simulation of Room Impulse Responses

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In many research fields of engineering and acoustics, the image-source model represents one of the most popular tools for the simulation of sound fields in virtual reverberant environments. This can be seen as a result from the relative simplicity and flexibility of this particular method. However, the associated computational costs constitute a well known drawback of image-source implementations, as the required simulation times grow exponentially with the considered reflection order. This paper proposes a method that allows for a fast synthesis of room impulse responses according to the image-source technique. This is achieved by modeling the diffuse reverberation tail as decaying random noise, where the decay envelope for the considered acoustic environment is determined according to a recently proposed method for the prediction of energy decay curves in image-source simulations. The diffuse reverberation model presented in this paper thus produces impulse responses that are representative of the specific virtual environment under consideration (within the general assumptions of geometrical room acoustics), in contrast to other artificial reverberation techniques developed on the basis of perceptual measures or assuming a purely exponential energy decay. Furthermore, since image-source simulations are only used for the computation of the early reflections, the proposed approach achieves a reduction of the computational requirements by up to two orders of magnitude for the simulation of full-length room impulse responses, compared to a standard image-source implementation.