Performance sensitivity of a tapped delay line filter is studied by varying system parameters such as tap coefficients, tap spacings, and the spectra and bandwidth of signal, noise, and directional noises. The optimum filter is designed both with and without the directional noise by using mean-square-error criterion for the case of single and multiple hydrophones. After prescribing the spectra of signal, noise, and directional noise, the performance sensitivity of the optimum filter is examined in detail for four characteristic tap spacings