Three Dimensional Noise Field Estimation from Horizontal Line Arrays

Abstract : A technique to estimate the three dimensional (3-D) character of the undersea ambient noise filed with the use of a horizontal line array as the measurement tool has been developed. Horizontal line array beam noise data, on several array headings, and knowledge of the array's 3-D beam response patterns were used as an input into the 3-D noise filed estimation technique. The final product indicates that the resulting 3-D field estimate can be used to determine both the horizontal and vertical directionality of the noise field. Furthermore, having an estimate of the 3-D noise field facilitates other investigations of the noise field that are normally not possible with either a vertical or a horizontal line array, such as the vertical directionality of the noise in a small azimuthal sector or the horizontal directionality at a particular elevation angle. It also appears that the use of horizontal line arrays and this 3-D technique could provide necessary measurement inputs to support design of volumetric array systems without the expense and/or technical difficulty of deploying a volumetric array.