Adding a masker-proximal interferer raises detection thresholds for a diotic pure tone.

Evidence

For the diotic 730-Hz target (top left panel), thresholds increase by 4.5 dB when an interferer was added at a distance of 30 Hz. For the spectral distance interferer-masker of 100 Hz, the threshold was 1.5 dB lower than for the spectral distance interferer-masker of 30 Hz. — Dijk, Pim van, Physiology, Psychoacoustics and…, 3484