Mutual radiation impedance
Complément : Complement
In the case when several vibrating surfaces exist, each surface "sees" simultaneously the reaction of the medium (air) to its own vibration and the pressure generated by its neighbors (mutual influence).
In this case, the radiation impedance is no longer a scalar but a matrix:
The non-diagonal terms ("mutual" impedances) are essential in the case of several sources arranged close one to another, such as, for example, the speakers network (line array) or a vented enclosure (proximity to loudspeaker and vent).
