Method to measure the efficiency and directivity index of underwater electroacoustic transducers

A method is presented to experimentally determine the electroacoustic efficiency and directivity index in any desired direction of underwater transducers. In the method, the far-field radiated pressure is measured at uniformly spaced points on the surface of a sphere enclosing the transducer to determine the intensity. A 2D Simpson's rule is used to integrate the intensity over the sphere and determine the radiated acoustic power. Sources of error are discussed. Typical measured values of efficiency and directivity index are also presented for free-flooded and Tonpilz transducers.