Low frequency noise from large wind turbines - quantification of the noise and assessment of the annoyance

In Denmark and abroad, erection of large wind turbines sometimes leads to adverse reactions from local society. This might prevent or delay projects for exploitation of wind power. One of the main reasons for these protests is fear of negative effects from noise, especially noise at low frequencies. For the moment there is only limited knowledge of the low frequency content in wind turbine noise and possible impacts. Thus, the risk of annoyance from low frequency noise can neither be confirmed nor disconfirmed. The main purposes of the project are to: 1. clarify whether noise from modern wind turbines has a significant content of low frequency noise/infrasound (or other characteristics which can be mistaken as such) and determine an appropriate method for outdoor noise measurements, 2. determine methods for prediction/estimation of the indoor level of low frequency noise/infrasound and the relation between the indoor and outdoor noise levels, 3. make an assessment of the annoyance of low frequency noise/infrasound from wind turbines, including an evaluation of the sound spectrum relative to the hearing threshold, 4. determine the natural background noise level and investigate its influence on annoyance. The project is expected to lead to greater validity in the assessment of noise annoyance from wind turbines, distance demands etc. for the benefit of citizens as well as electric power utility companies. Depending on the extent of the problem, the project can help wind turbine manufacturers focus their work against noise and include noise as a competitive parameter