Ships underwater noise measurements using sound intensity method

pp. 53-60, vol. 12, 2009

Ignacy Gloza
Polish Naval Academy in Gdynia, Gdynia, Poland

Key words: spectrogram; near acoustic field; PULSE measuring system

Abstract: Ship noise is a most important part of the field of underwater acoustics. Its reduction and monitoring is an important aspect in the performance of underwater acoustic systems and in the habitability of the vessel for the crew and passengers. In naval operations the noise radiated by a ship is also dominant source of information for underwater sonar systems. Sound intensity is the vector quantity which informs us about the sound power flux, the position and the direction of the sound source. The probe tracks the position of source and at the same time, measures the component of sound-intensity vector. Generally only one component of vector sound intensity was measured, perpendicular to a given measurement surface. The sound intensity of a moving source includes effects such as flow noise that are not present when the source is stationary. The accuracy of measuring acoustic intensity using two closely spaced hydrophones by correcting the phase mismatch error by measuring the transfer function between the two detector systems was examined. The two measuring hydrophone instrumentation systems were earlier calibrated. Our results have been obtained using digital methods, where was used PULSE measuring system.

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