Simulation Study on Spatial Distribution Characteristics of Incoherent Sound Fields in Horizontally Layered Media

To investigate the vertical distribution of ocean acoustic fields and to provide a theoretical basis for passive source depth estimation, research on spatial distribution of incoherent acoustic fields is conducted in this paper. The analytical expression for incoherent acoustic field intensity is theoretically derived based on an ideal waveguide model. Theoretical analysis reveals that the maximum intensity consistently appears at or near the source depth for a given horizontal range, and this distribution pattern is independent of propagation distance. To test the generality of this characteristic in complex environments, numerical simulations are conducted using a normal mode model for two horizontally stratified media: shallow water and a typical deep-sea sound channel. Simulation results show that, with the exception of one special case, the vertical distribution of incoherent acoustic field intensity closely follows that of the ideal waveguide, with the maximum occurring at or near the source depth. The sole exception occurs when a surface duct exists in the deep-sea sound channel and the source is placed inside that duct, causing the maximum intensity to shift away from the source depth. These results confirm the robustness of this vertical distribution characteristic in horizontally stratified media and offer a novel approach for passive source depth estimation.