On the detectability of a wind turbines noise under different meteorological conditions

Long-term measurements for monitoring the noise immission of wind turbines (WT) are difficult because the local noise level is determined by a variety of influences [1]. On the one hand, there is the highly variable emission level, depending on the inflow conditions and on the rotational speed of the turbine. On the other hand, an assignment of the noise to the source is not always clear, because the immission level is often on the same level as the external noise. To improve the understanding of the sound transmission under different meteorological conditions such an assignment of the source noises is essential. The aim of this paper is to show which immission measurement data can be used to evaluate sufficiently high-resolution (temporal and spectral) long-term measurement data to obtain information on sound emission, rotational speed, background noise, amplitude modulation and the local noise exposure coming from a wind turbine. The long-term measurements compare different meteorological conditions and show the influence of the weather on the detectability of the WT noise. These investigations allow statements about the necessary analysis periods, the consideration of meteorological information and new metrics in noise monitoring.