Statistical analysis of ship noise records

A statistical analysis of noise can play an important role in evaluating the performances of an acoustic system working underwater. If the system is either placed on board a vessel or operates nearby passing ships, the noise radiated by the vessel can considerably reduce the performances of the system if it has been not designed to have enough robustness. In the paper, a statistical analysis of ship noise records measured at sea is presented. Noise data were recorded in the framework of the EU FP7 European project AQUO (Achieve QUieter Oceans by shipping noise footprint reduction). Aim of the analysis is to characterize the ship noise in terms of probability distributions and their high-order moments. Since the overall ship noise is known to be generated by a number of sources with peculiar spectral energy distributions, the vessel spectrum can change considerably with a variation in the operating conditions. This approach allows determining the dependence of ship noise statistical properties on the actual navigation condition. In addition, since the ship noise records were simultaneously recorded by a vertical array of three hydrophones, a further analysis has been carried out to determine the effect of the receiver depth, and, accordingly, of the propagation path, in the recorded signal.