M. K. Beason
Naval Res. Lab., Underwater Sound Ref. Detachment, P.O. Box 568337, Orlando, FL 32856-8337
D. H. Trivett
Texas Res. Inst.
L. D. Luker
Naval Res. Lab.
Generally, the measurement of sound pressure in water is not significantly affected by the small acceleration sensitivity of the hydrophone. In a standing-wave tube, however, regions exist with very large particle velocities and small pressures. The acceleration sensitivity of the hydrophone can, therefore, cause a large error in the measurement of the pressure. The long-line-hydrophone calibrator (LLHC) uses the electroacoustic transfer matrix of the system to determine the projector drives required to simulate a plane-wave pressure field within the calibrator. The algorithm employed operates the calibrator as a standing wave tube to measure the transfer matrix. Thus measurement inaccuracies caused by acceleration-sensitive hydrophones will affect the quality of the field. A hydrophone design is presented that reduces the acceleration sensitivity by using spherical piezoelectric elements and ``free-floating'' mounts. Results are also presented that compare relative measurements of pressure errors caused by hydrophone acceleration sensitivity in a standing-wave tube. [Work supported by NAVSEA.]