Identification methods of underwater noise sources generated by small ships

Abstract

In this work we were interested in the use for the localization of the ship noise sources in the water environment. Particular interest was dedicated to identifying of narrow band contribution to the total spectra of the ship hydroacoustic noise. The analyses were performed in time and frequency domain. The diesel engine, the electric motor and the propeller have notably been studied and the different frequencies connected to these devices have been listed. Extensive measurements were made of the underwater radiated noise of K1 and K2, small vessels powered by an electric and diesel engines. The discrete Fourier transform and the short time Fourier transform and sound intensity method were used for a precise analysis. The coherence function was also performed to associate each component of underwater noise with the vibrating part of the engine, which generates it. The measurement results obtained here have been later analyzed and a criticism of each method has been done, focusing on its advantages in the field of the identification of the noise sources.