Generalized alternative image theory to estimating sound field for complex shapes of indoor spaces

摘要

An alternative image theory that can efficiently simulate sound propagation inside a closed space, especially multiple reflections, is proposed. This method defines image spaces according to configuration of a real space, and image receivers instead of image sources are allocated with respect to their local coordinates. As compared to the original image theory, the alternative theory is more effective to develop propagation paths involved with reflections regardless of condition variables such as the number of reflections and combinations of reflecting surfaces. The positions of image receivers located in an image space corresponds to where sound waves that experiences the specific number of reflections related to the order of the image spaces reach to real receivers. Therefore, the sound field inside the real space is obtained by inverting the entire image spaces into the real space, which implies superposition. Basically, it is applicable to convex spaces, e.g. a rectangular hexahedron. Also, concave spaces and spaces that have partitioned into sub-spaces can be covered by the alternative theory.