  Differences in interaural phase configuration between a target and a masker
can lead to substantial binaural unmasking. This effect is decreased for
masking noises with an interaural time difference (ITD). Adding a second noise
with an opposing ITD in most cases further reduces binaural unmasking. Thus
far, modeling of these detection thresholds required both a mechanism for
internal ITD compensation and an increased binaural bandwidth. An alternative
explanation for the reduction is that unmasking is impaired by the lower
interaural coherence in off-frequency regions caused by the second masker
(Marquardt & McAlpine, 2009, JASA pp. EL177 - EL182). Based on this hypothesis,
the current work proposes a quantitative multi-channel model using monaurally
derived peripheral filter bandwidths and an across-channel incoherence
interference mechanism. This mechanism differs from wider filters since it has
no effect when the masker coherence is constant across frequency bands.
Combined with a monaural energy discrimination pathway, the model predicts the
differences between a single delayed noise and two opposingly delayed noises,
as well as four other data sets. It helps resolve the inconsistency explaining
some data sets requires wide filters while others require narrow filters.
