The use of equivalent source models for reduced order simulation in room acoustics

Abstract

The sound field in a room can be predicted by using the Boundary Element Method if the motion of the source is known along with the impedance of the room surfaces and furnishings: however, these computations are very time consuming, especially at high frequencies. It is known that the total sound field in a room consists of three components: (1) free space source radiation; (2) the incoming sound field reflected from the room surfaces; and (3) the outgoing sound field scattered from the source surface, particularly if it is large: e.g., a flat screen television. For the purpose of fast computation, an equivalent source method (ESM) can be adopted in which two sets of equivalent sources represent the incoming and scattered sound field components, respectively. When the free space component is known, the parameters of the ESM can be estimated by least squares approximations of the impedance boundary conditions on the room and source surfaces. Accuracy and computational load can be balanced by the choice of source order and the constraints placed on equivalent source locations. Simulation results will be presented to compare the performances of different ESM configurations.