Estimation of acoustic reflection pattern using multi-point impulse response and spatial Fourier transform

Abstract

We propose a method using impulse responses (IRs) measured at multiple points to evaluate the acoustic reflection of materials. This method combines responses with appropriate delays and estimates the reflection patterns of arbitrary incident waves. IRs are measured for all combinations of sources and receivers, which are arranged in a grid pattern on planes. Further, postprocessing can estimate the directions of the incident and reflected waves. This is equivalent to synthesizing a wavefront using the sound field reproduction technology. Direction-of-arrival (DOA) estimation was performed by applying a spatial Fourier transform to the processed sound pressure. Numerical simulations were conducted for plane-wave incident conditions using impulse responses generated by the mirror-image method, assuming that the material surface is rigid. The numerical results demonstrate that the proposed method can accurately estimate the reflection pattern when a plane wave arrives in an arbitrary direction. However, as the incident angle becomes almost parallel to the material surface, that is, at grazing incidence, synthesizing wavefronts with sufficient accuracy becomes more challenging.