A sonar system for detecting underwater acoustic signals includes a plurality of hydrophone units capable of converting acoustic impulses to electrical signals, the hydrophone units being substantially vertically oriented when deployed in a body of water, and the hydrophone units occupying at least some of the positions of an M×N horizontal array. Two-dimensional Chebyshev mathematical weighting is applied to the electrical signals from the individual hydrophone units such that each individual signal from each hydrophone unit is assigned a respective weighting number and a numerical value is assigned to each individual signal corresponding to the strength of the electrical signal as adjusted by the respective weighting number.