on the localisation in the superimposed soundfield - Hauptmikrofon ...

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2. .The “phantom source”
An important special case of localisation in the superimposed sound field is if several
sound events are mapped to a common auditory event, so that its location does not
correspond to the ones of the sound sources. This case is referred to as a “phantom
source”, since an auditory event is perceived to be at a position where no sound source
is actually located.
Yet, bearing in mind the definitions given above, the term “sound source” cannot be
utilised for describing an auditory event. In the literature, a phantom source is thus
also interpreted as an imaginary, fictitious sound source, with the help of which one
tries to describe the physical side of the localisation process. One proceeds on the
assumption that, in principle, a phantom source constitutes a substitute sound source
producing the same ear signal characteristics in its sound field as it would in a
corresponding superimposed sound field at the same listening position.
As will be shown below, in many cases serious objections have to be raised with
regard to this assumption (see Sections 2.2 and 4.2). Nevertheless, for the time being,
the term “phantom source” shall be used to characterise particular sound field
constellations in the usual manner. Unless specified otherwise, “phantom source”
specifically refers to the sound field produced by two coherent signals that are played
back over a conventional, loudspeaker-based stereo set-up (see Figure 1).
Figure 1:
Conventional, loudspeaker-based stereo set-up
This special case of localisation in the superimposed sound field is not just of
particular relevance to the electroacoustic reproduction of spatially distributed sound