Analysis of Electroacoustical Transducers by Differential Immittance Techniques

Techniques are in use for the measurement and recording of the impedance and admittance loci of electroacoustical transducers at various levels of input power. The resulting data are used for determining properties such as piezoelectric coefficients, mechanical Q, resonant frequency, potential efficiency, etc. An extension of these techniques has now been developed to provide direct measurements and graphic recordings of the difference between two admittances or impedances. This approach may be used to separate the motional impedance or admittance circle from the complete locus without the need for lengthy arithmetical manipulations and also to read the minor component of impedance or admittance with greater accuracy than has heretofore been possible in direct-reading systems. This approach has also been applied to the measurement of the dielectric loss and capacitance of piezoelectrics under high voltage and to the separation of time-variant components of impedance from time-invariant components.