In-situ estimation of acoustic impedance on the surfaces of a room for inverse sound rendering

We present a method based on the inverse boundary element method (IBEM) for the in-situ estimation of normal acoustic impedances of the surfaces in a room. As input to the inverse process, this technique uses the geometry of the interior space, the position and strength of the sound source, and a set of sound pressures measured at random positions in the acoustic field. Previous work in inverse radiation problems has employed computational expensive techniques such as singular value decomposition (SVD) in order to obtained satisfactory results. In contrast, the numerical simulations of the present work show that the least-squares approach can give satisfactory solutions when the linear system of the formulation derived here is sufficiently overdetermined with sound samples taken at random locations in the interior. The use of 3D stereo vision tracking is suggested to enable the practical measurement of large sets of field pressures. Currently, inverse sound rendering for virtual reality (VR) is a targeted application of our method.