ASA 126th Meeting Denver 1993 October 4-8

4pED8. A simple water-filled compliant-tube calibrator.

David L. Gardner

CDR, NOAA Pacific Marine Environmental Lab., 7600 Sand Point Way, N.E., Seattle, WA 98115

Thomas B. Gabrielson

NAWC Aircraft Div., Warminster, PA 18974

Several geometries for low-frequency underwater calibrations are in common use, but often require either anechoic walls, rigid walls, or tanks (or lakes) of large dimensions with respect to a wavelength. Such facilities are frequently not practical for use in teaching laboratories either because of inaccessibility or because the facility must be shared with active researchers. The compliant, water-filled cylindrical tube described in this paper permits low-frequency calibrations in a laboratory environment, with modest cost and size. The sound speed inside one such device is approximately 300 m/s, which allows 100-Hz measurements in tubes 1 m long. The limitations of the compliant tube calibrator and examples of measurements made using the calibrator will be discussed.