Laboratory Calibration of a Receiver for Measuring the Underwater Noise Levels of a Ship

The calibration in a laboratory hydroacoustic tank of a receiver, used to measure the level of underwater noise under natural conditions, is considered. The idea of receiver sensitivity over a 1/3-octave frequency band is introduced and a method of determining it from the detailed frequency characteristic of the receiver is proposed. It is shown how one can overcome the complexity due to scattering from the structure surrounding the hydrophone in the receiver, which manifests itself as an increase in the effective size of the receiver and the distance of the far field when it is calibrated.