Development, validation and publication of a complete model for hydrophone/amplifier transfer characteristics.

A complete theoretical model for the transfer characteristics of a 25 mm film thickness 0.5 mm diameter bilaminar hydrophone has been developed and validated as part of project 4.4.3 of the DTI National Measurement System Programme for Acoustical Metrology, 1998-2001. The model includes: · the possibility to model one-dimensional acoustic propagation in multi-layered media using a transfer matrix formulation · secondary piezoelectric effects · the electrical effects of the leg, modelled as a distributed series resistance/shunt lossy capacitance network · the hydrophone coaxial cable, modelled as a transmission line, followed by a load if required · the amplifier transfer characteristics, the properties of which are to be obtained from measurement. Precision Acoustics Ltd has contributed to this project by producing measurements of some of the model input parameters. The open-circuit response predicted by the model compares well with calibration results and varying the model input parameters within plausible ranges appears to reproduce the trends observed in the responses of calibrated devices.