General Reciprocity Parameter

The reciprocity parameter used in the reciprocity calibration of electroacoustic transducers is derived for the general case of arbitrary boundary conditions and arbitrary definitions of responses. A general reciprocity parameter is defined as the ratio of the volume velocity emanating from a surface defined in the transmitting response to the resulting pressure averaged over a surface defined in the receiving response. It is shown how the general parameter concept leads directly and simply to the various special parameters for the cases of spherical waves, cylindrical waves, plane waves, diffuse sound, couplers, and tubes. Application of the concept to in situ and nearfield conditions is also described.