2013 Volume 26 Issue 1 Pages 81-90
ABSTRACT : The purpose of this study is to make a contribution to the development of the evaluation techniques for environmental impacts of underwater noise from offshore wind turbines. In this study, the authors measured the underwater noise from a fixed offshore wind turbine during construction (installation of monopile foundation). By analyzing the data, the time series and frequency characteristics of underwater noise and the effect of piling on sound levels were clarified. Besides, in order to get the properties of sound propagation in the construction area, the authors measured the regular waves of some frequencies from an underwater speaker while the piling was stopped. From the measured data, the transmission loss was estimated and the attenuation curve was made. With this curve, the sound source pressures were estimated from the measured sound levels and the distances between the piling point and the measuring points. Moreover, it was revealed that there was a correlation between the estimated sound source pressures and the energy of hammering.
