Estimation of the source distance using the multiple three-dimensional acoustic intensimetry

Abstract

A 3D acoustic intensimetry (AI) in tetrahedral configuration can be used for the source localization. Such a 3D AI module is compact, but also it can yield a precise bearing angle for the low Helmholtz numbers if some bias errors are compensated. In this study, besides the bearing angle, the source distance is estimated by using the multiple 3D AI probes with different acoustic centers. Because each AI module indicates a vector from the acoustic center to the source direction, the nearest point between any pair of line vectors can approximate the source position. The source position can be estimated by minimizing the least square error of the positions determined by multiple intensity vectors. Such idea is preliminarily tested with four 3D AI modules, of which each module is composed of 4 MEMS microphones separated by 30 mm. Four 3D AI modules are also arranged in a tetrahedron layout, and the source frequency range is 0.5-2 kHz. The distance between modules is varied for 150-250 mm range, and the source distance for 1-4 m range. Current test results reveal that the estimation error is less than about 2, 5, 7% when the elevation angle is within 0-30°, 30-60°, 60-90°, respectively.