Sound sources in reverberant environment.
The sound, which arrives within rooms at a listener's ears, consists of direct sound and sound, which has been reflected at the room's walls. The reflected sound can be described by so called "mirror sound sources".
For all possible paths, which can be taken by the sound on its way from the real sound source to the listener's ears a mirror sound source is introduced, which emitts the same sound than the real sound source. The sound of each mirror sound source propagates on a straight line to the listener's ear. Wall reflections are modelled by virtual wall transmissions; the reflection and absorption characteristics of the walls are substituted by corresponding wall transmission characteristics.
When attention focusses on the direction of the real sound source, the Cocktail-Party-Effect suppresses sound from other directions. Applying this to the mirror sound source modell, it means, that in reverberant environment the Cocktail-Party-Effect extracts only the sound of the real sound source and the sound of mirror sound sources with similar directions than the real sound source. As a consequnce most mirror sound sources are suppressed, echoes and reverberation are significantly reduced.