Interference between a target and simultaneous maskers occurs both at the cochlear level through energetic masking (EM) and centrally through informational masking (IM). Quantifying the amount of IM requires a strict control of the energetic component. Presenting target and maskers dichotically reduces EM, but provides listeners with important lateralization cues that drastically reduce IM. Here, we restored most of the IM in dichotic sequences by alternating the presentation sides of a regularly repeating target and a randomly varying background masker. This manipulation thus provides an original tool to isolate IM in signal and maskers having overlapping spectra.