Noise spectra comparison among wind turbinesand its implications to human perception.

The noise coming from wind power development can be an environmental impact forthe surrounding communities. It is well known that the main wind turbine noise iscaused by the movement of the turbine wings through the air. However, there areuncertainties about the importance of machinery sounds and possible variations amongwind turbines. A high resolution acquisition system was used to perform a fieldexperiment comparison of the noise spectra from some wind turbines at Laholm(Sweden). The results have shown different band spectra peaks associated to machinerysounds among wind turbines from the same model and also from those of differentmanufactures. Maintenance conditions of these wind turbines could explain thedifferences in intensity and frequency locations of the band spectra peaks found. Inorder to know the importance for human audition of these peaks, listening test or doseresponsestudies would be needed to provide relevant information in this regard. Themethodology developed in this study is suggested to be useful for identifying certainmachinery failures which could corrupt the noise sounds emitted at certain wind turbinelocations