A phantom image is the illusion of an independent sound source created by two or more loudspeakers. Most
often created by manipulating level differences between stereophonic channels (aka, panning), the effect is
used to create a sense of auditory space between loudspeakers and is largely taken for granted. This research
examined the efficacy of phantom image perception horizontally and vertically from an active listener
perspective. After listening to a target loudspeaker, listeners (n = 442) were asked to move a phantom sound
to a position to match that of the target loudspeaker. The listeners phantom placement was then compared
to the target, and subjects were allowed to adjust their phantom position. The horizontal experiment was
based on a standard stereophonic 60 loudspeaker array with the target loudspeaker at 15 off center. The
vertical experiment utilized elevated loudspeakers on a 60 arc with the target loudspeaker elevated 10 above
the horizon (lower loudspeaker). Results show nearly universal undershoot in horizontal placement on first
attempts with gradual improvement over trials that coalesced around the projected target location. However,
after repeated tries, the final phantom image positions were spread over 2/3 of the left sound field around the
target loudspeaker. In the vertical trials phantom placements were spread across the entire sound field in all
three trials and failed to show any patterns of convergence towards the target loudspeaker.
(See document for exact affiliation information.)
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