Manifold Characteristics of Tetrahedral Acoustic Vector Array

Acoustic vector sensors (AVSs) can be employed to improve low-frequency performance of the sensor array against aperture limitation, due to their configurations that allow for the simultaneous measurements of sound pressure and particle velocities. This article proposes a tetrahedral vector array composed of four triaxial vector sensors with particular emphasis on the manifold characteristics in comparison with the tetrahedral scalar array of the same aperture and channel number in near-field and far-field. The Cramér-Rao bounds (CRBs) are further derived to analyze the lowest performance boundaries for both the scalar and vector arrays. Numerical simulations are conducted to evaluate the performance of the tetrahedral arrays in terms of the root-mean-square error (RMSE), mainlobe, and dual-source resolution. Compared to the scalar array, the vector array provides narrower mainlobe widths and more accurate localization estimations. Moreover, the vector array is particularly useful in identifying two sources at lower frequencies and smaller azimuth intervals. To support the theoretical and simulation findings, measurements are made in a full anechoic chamber to assess the performance of the tetrahedral arrays for single-source and dual-source localization. Experimental results confirm that the low-frequency performance of the tetrahedral array is greatly enhanced by adopting the vector sensors due to the anticipated advantage of the manifold characteristics.