Thin, low-frequency sound projectors for use in shallow water

A thin, low-frequency acoustic projector is being developed at the Naval Research Laboratory for shallow water applications. The active panel consists of cymbal-type flextensional driver elements arranged individually behind an acoustic radiating plate. Variants of two panel designs have been calibrated underwater. The acoustic projector sandwich is nominally 6.35 mm thick and is intended to operate between 1 and 10 kHz. The calibration results that will be presented (TVR, SPL, directivity response) will focus primarily on a panel consisting of 12.7-mm-diam cymbal elements arranged in an 8×8 square configuration. [This research is being supported by Code 321SS of the Office of Naval Research.]