Estimation Of The Three Dimensional Underwater Ambient Noise Field From Horizontal Line Array Data

Abstract : Several algorithms and techniques have been developed to estimate the horizontal directionality of ambient noise from horizontal line arrays. In most cases, the two-dimensional (2-D) representation of the array beam pattern is adequate to estimate the ambient noise horizontal directionality. However, when significant amounts of the noise are distributed out of the horizontal plan, a 2-D representation of the noise field can be misleading. An algorithm is described herein that utilizes the three-dimensional conical nature of the beam response patterns of the towed array and an iterative technique to estimate the 3-D ambient noise directionality. The algorithm is described and results form actual at-sea measurements are presented. This work was supported by funding from the Antisubmarine Warfare Environmental Acoustic Support (AEAS) Program of the Office of Naval Research.