The Potential of Natural Sounds to Mask Wind Turbine Noise

Wind turbine (WT) noise may cause annoyance, especially in relatively quiet areas with low ambient levels. As a compliment to conventional noise control at the source, addition of wanted sounds may reduce the loudness of WT noise by auditory masking. In order to test this, two masking experiments were conducted with two WT noises as target sounds and three natural sounds as maskers (wind in coniferous or deciduous trees and sea waves). In the first experiment, 30 listeners determined the detection thresholds of WT noise in the presence of the natural sounds using a threshold tracking method. In the second experiment, the same group of listeners matched the loudness of partially masked WT noise with the loudness of unmasked WT noise. The results showed that detection thresholds for WT-noise in the presence of natural sounds from trees and sea waves were around −8 to −12 dB S/N-ratio. Furthermore, a reduction of perceived loudness of WT-noise was found for S/N-ratios up to 2 dB. These results were compared with predictions from two models of partial masking (steady and time variant). In general, empirically determined detection thresholds and partial loudness matches were higher than predictions from the two models.