The Journal of the Acoustical Society of America | 5 Nov 2013
R Carman and M Amato
Area-wide measurements of low frequency wind turbine noise were conducted in residential areas adjacent to two different wind turbine facilities in Southern California. The residential measurement location distances ranged from 615 m to 9 km from wind turbines. Additional measurements were also conducted at distances as close as 125 m from the wind turbines. To obtain the residential measurement data, simultaneous digital recordings were made inside and outside residences using microphones designed to achieve a linear response down to 0.07 Hz. The outdoor measurements were conducted with a ground board and two windscreens. The recorded data at residences were analyzed using a cross-spectral technique to minimize the effects of wind acting on the microphone. The data clearly show the presence of infrasound at the blade passage frequency of the wind turbines as well as at the associated harmonics. The primary range of interest is frequencies between 0 and 10 Hz. The residential data in some instances indicate higher levels of infrasound indoors compared to outdoors, indicating a potential amplification of very low frequency sound energy by the residential structure. Representative infrasound data for both facilities are presented and discussed.
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