Abstract Using rippled noise probes, spectrum-pattern resolution was measured with and without a narrow-band noise masker. Diotic presentation of both the probe and masker (S 0N 0 mode) resulted in decreased spectrum resolution as compared to the control (no masker) conditions. The effects of the low- and on-frequency maskers differed quantitatively, however in both cases the ability to discriminate the probe spectrum pattern was suppressed completely when the masker/probe level ratio exceeded 10 dB (on-frequency masker) or 10–25 dB, depending on the probe level (low-frequency masker). The effect of the high-frequency masker was negligible. Slight but noticeable releasing of the spectrum-pattern resolution was found when the probe was presented to both ears in-phase and the masker counter-phase (S 0N π mode). In conditions of the probe delivered to one ear and the masker to the other ear (S LN R mode), the effect on the spectrum-pattern resolution was slight or negligible within a wide range of the noise/probe ratio.