| dc.description.abstract | The geometric spreading correction for noise level measurement is not so accurate since the noise also affected by the surface and bottom reflection. The surface reflection interference is called Lloyd mirror effect. A model to reduce the Lloyd mirror effect was designed. Thereby more accurate noise spectrum of ships can be obtained, the origins of the noise generator can be found. Further more increasing the catch rate.\\
The experiment was conducted on Gunnerus(a research vessel belong to NTNU) in Trondheim fjord, September, 2018. The hydrophone located close to the sea bottom and the vessel following straight tracks of \SI{1}{km} and passing the hydrophone. The result of the experiment confirmed that the Lloyd mirror effect interfered the measured noise level. By using the inverse model, the Lloyd mirror effect was reduced in some extent. | |
