In a comparison of tonal and narrow‐band signals, reported by the authors in 1964, the masking level differences (MLD's) for the two signals were the same for corresponding phase shifts. Earlier, Hirsh and Webster reported differences for similar conditions. In the authors' experiment, there was a random phase difference between the signal and masker since separate noise generators provided the signal and noise, while Hirsh and Webster's single noise generator gave a fixed phase difference between the signal and masker. In the present experiment, a single noise generator was used and the phase difference between the signal and masker was shifted in phase by 30° steps between 0° and 180°. For each signal‐masker phase difference, the signal was presented in phase at the ears and reversed in phase at one ear. Data are presented as MLD's relative to the signal‐in‐phase condition for each signal‐masker phase difference. The MLD's increase monotonically from 13 dB at 0° to 18.5 dB at 180°. [Work supported by USN Bureau of Ships contract NObsr‐72627 and under a grant from the National Aeronautics and Space Administration R‐129 through ONR contract 3579(04).]