Statistical characterization of the ship as a source of noise by means of acoustic range surveys

In the present work the main problems regarding the experimental characterízation of the ship as a source of noise are overviewed. A number of surveys carried out at an acoustic range are studied by means of different regression analyses in order to find the best correspondance wlth the measured values. The investigation is performed with the aim of determining and quantifing the influence of various physical parameters involved in noise propagation in water: (distance, transverse angular position, water depth, difference between the direct and the surface-reflected path). The model derived from the regression analysis is utilized to solve the practical problen of referring the noise surveys at an acoustical range to the conventional distance of one metre: a comparison is presented with the results obtained using other methodologies based on simple mathematical models or on experimental transnission losses.