Stationary visual targets often become far more salient when they move against an otherwise static background-the so-called "pop out" effect. In two experiments conducted over loudspeakers, we tested for a similar pop-out effect in the auditory domain. Tone-in-noise and noise-in-noise detection thresholds were measured using a 2-up, 1-down adaptive procedure under conditions where target and masker(s) were presented from the same or different locations and when the target was stationary or moved via amplitude-panning. In the first experiment, target tones of 0.5 kHz and 4 kHz were tested, maskers (2-4, depending on the condition) were independent Gaussian noises, and all stimuli were 500-ms duration. In the second experiment, a single pink noise masker (0.3-12 kHz) was presented with a single target at one of four bandwidths (0.3-0.6 kHz, 3-6 kHz, 6-12 kHz, 0.3-12 kHz) under conditions where target and masker were presented from the same or different locations and where the target moved or not. The results of both experiments failed to show a decrease in detection thresholds resulting from movement of the target.
Keywords: spatial hearing; spatial release from masking.