Auditory spatial perception with sources overlapping in frequency and time

The effect of a broadband masker on the localisation of a broadband target stimulus was investigated. Human listeners identified the perceived location of the target stimulus, which was randomly presented with and without the masker. Five stimulus conditions were examined, in which the temporal overlap and total duration of the pair were varied. It was found that, overall, localisation was quite robust in the presence of the masker. However, a small and systematic bias in lateral angle perception that was directed away from the lateral angle of the masker was observed. The effect was most pronounced when the target and masker overlapped in time, and was nearly eliminated when the masker fully preceded the target. Furthermore, the effect was not restricted to stimulus pairs in close proximity. Disruptions to polar angle localisation were far less systematic, varying in both magnitude and direction. In general the results were not consistent with previous models that incorporate spatial channel interactions. When stimuli overlap in both frequency and time, it is likely that interference in the processing of acoustic localisation cues influences perceived location.