phantom sound source (acoustics)
A phantom sound source is a virtual sound source created by two identical loudspeakers driven with the same signals.
If two identical loudspeakers are driven with the same signals in terms of frequency, level and phase, then the listener locates both sound sources as one sound source centered between the two sound sources. This configuration is a phantom sound source. The prerequisite for this is that the loudspeakers are driven with identical signals and that there are also the same propagation times between the loudspeakers and the listener. Even the smallest deviations of 1 ms no longer cause a phantom effect. The listener then hears the sound source with the shorter propagation time. With even smaller runtime differences, the listener already perceives volume differences.