Reciprocity Calibration in a Compliant Cylindrical Tube.
NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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A new method for absolute calibration of electroacoustic transducers is described which permits low frequency reciprocity calibration in a test apparatus of small dimensions. The method takes advantage of the reduced wave speed in a cylindrical water column bounded by a complaint PVC tube to reduce the length of the standing wave to dimensions which can be easily handled in the laboratory. Results of a limited series of experiments show a mean reproducibility of - 0.8 decibels in a one-meter long tube at frequencies between 750 and 1100 Hz and sound speeds from 330 to 365 meterssecond. The hydrophone voltage sensitivities obtained by the method, however, systematically differ by 1.5 decibels from those measured by comparison with a standard hydrophone additional research will be required to resolve this discrepancy. Originator supplied keywords include Low-frequency underwater acoustic transducer calibrations.
- Test Facilities, Equipment and Methods