A solution to the problem of bearing estimation of multiple sound sources in a shallow ocean waveguide is developed. A planar array of N vertical columns of Q hydrophones each is used. Each vertical column is used as a mode-filter to extract the same normal mode from among the many propagating in the waveguide. It is shown that a two-column planar array used in conjunction with a delay-and-sum array processor would suffice to estimate the source bearing. When multiple sources are present, the

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... e of a high resolution spectral estimation technique in place of the simple delay-andsum array processor provides unbiased estimates. Computer simulation results using the MUSIC method with a planar array in a waveguide tiith a rigid bottom are presented.