To locate a sound source the angle of incidence of the so-called First Wave Front is evaluated by the human ear ('Stereophonic Sound Localization'). The 'First Wave Front' contains all sound waves (including reflected waves) of a sound pulse being sent out from a sound source arriving within 1-2 msec at the human ear.

The deviation of the incident direction of the 'First Wave Front' from the reference direction (e.g. sound source to listener) is described in CARA by the so-called Location Reference Number. The 'Location Reference Number' may vary between +1 and -1. A 'Location Reference Number' of +1 indicates that the incident direction matches perfectly with the reference direction, -1 indicates that the incident direction is opposite to the reference direction.

The Location Diagram shows the frequency dependence of the 'Location Reference Number' at the listening place (green curve).

The red curve for the Total Sound shows that the incident direction is no longer constant but is varying very much, the sound waves propagation is diffuse. This curve is of no practical relevance and is presented only as an additional information.