Double tetrahedral intensity probes for reducing the spatial bias error of source localization

Abstract

A compact tetrahedral probe used for measuring the three-dimensional acoustic intensity vector can be used for the source localization. Although such 3D intensimetry is advantageous in miniaturizing the sensing system size, it has not been popularly used due to its large spectral and spatial bias errors, which are additional to the bias errors at low and high frequency ranges. Compensation methods for spectral bias errors are recently proposed, but the spatial bias error, which is related to the probe orientation, is not easy to compensate. In this work, the idea is to adopt two probes together, thus effectively arranging the microphones to reduce the spatial sparseness of sensors and the irregularity in directivity. The number of microphones is minimized by sharing 1 or 3 microphones in the double module probes, while permitting the calculation of two intensity vectors. Two different types of probe configurations are used: twisted double probes, double tetrahedral probe symmetric to a face of the tetrahedron. A numerical simulation is conducted to compare the proposed probe systems with single probe. The result shows that the residual spatial bias error is less than 5.7° for 2.5<kd<4.1 range.