Source depth estimation based on the higher-order sound field in the deep ocean

Lloyd's mirror effect is a spatial interference phenomenon that results from the coherent combination of direct and surface-reflected propagation paths. The higher-order vertical sound intensities of the interference sound field contain source depth information, and the relationship between these higher-order sound intensities can be employed to estimate the source depth. A method for source depth estimation and qualitative binary source depth discrimination using the 0th-order sound pressure, as well as the 1st- and 2nd-order sound intensities, was proposed. The numerical simulation results confirmed the ability of the proposed method to approximate the source depth and discriminate between surface and submerged sources without requiring long-term tracking or knowledge of the ocean environment.