Results from background noise measurements in the North Sea

Abstract

In Germany, 12.8 GW offshore wind power shall be installed until 2023, which involves that at minimum 200 wind turbines need to be erected each year. As the majority of the turbines’ foundations are based pile driving vast amounts of high level impulsive noise are introduced into the North- and Baltic Sea. Until today, research on pile driving noise largely focuses on sound propagation and noise mitigation in close vicinity of the pile. Further effects of impulsive noise in larger distances over 10 km are rather unknown due to a lack of knowledge on the propagation and on the effects of noise at levels below injury. The German Agency for Nature Conservation has founded a campaign to measure underwater noise in the marine protected areas of the German EEZ. In this course, 10 noise recorders are simultaneously deployed in the large protected area Sylt Outer Reef. At least three wind farms are to be installed in the area’s vicinity; therefore, recordings of background noise during the installation phase allow a systematic investigation of impulsive noise propagation over large distances. Results in time domain and in frequency domain are compared with results from commonly available calculation codes.