Before construction started and during some of the pile-driving operations an underwater microphone was suspended from a ship at precisely determined locations. A computer recorded the signals so they could be analysed. The characteristics of the seabed are not the same at each wind turbine location, so the energy needed to drive a foundation pile into the ground is not the same everywhere. The pile-driving operations where readings were taken were determined specifically with the aim of establishing the effect that the location has on the noise level of the pile-driving. Separate reports will appear with the results of the surveys before and during the construction. They will be published later this year. The following underwater noise measurements will be carried out when the wind farm is in service. The ultimate aim of the noise survey is to determine the effect the noise made underwater by the wind farm has on the wildlife in the vicinity.