Effect and mitigation method of the sea surface interference on the underwater ship radiated noise measurement

Owing to the impact of sea surface interference,the observed results of underwater radiated noise from vessels usually were inaccurate.Three approaches were proposed to mitigate the influence of sea surface interference:averaging across the time,averaging across multiple hydrophones,presenting the data in terms of the One-Third Octave(OTO)bands rather than as narrowband data.The effectiveness of the approaches were validated by ray model.According to the standard released from International Organization for Standardization(ISO),the underwater noise radiated from a new research vessel was measured.During the data collection,the Vessel sailed at different speeds.Furthermore,the one-third octave sound band pressure levels of the radiated noise at different speeds were calculated and compared with the standard SLIENT-E published by the DET Norske Veritas(DNV).Analysis result indicated that the low frequency radiated noise of the research vessel is well controlled,but the high frequency part is poor suppressed.