Microsoft Word - Maastricht - Moeller et al 2011.docx Assessment of low‐frequency noise from wind turbines in Maastricht1 By Henrik Møller*, Steffen Pedersen*, Jan Kloster Staunstrup** and Christian Sejer Pedersen* *Section of Acoustics, **Department of Development and Planning, Aalborg University, Denmark 1 Preface The noise from a planned wind‐farm project at Lanakerveld in Maastricht has been evaluated in several reports. Boukich and Koppen1 studied alternative projects, and Koppen2 made additional analyses including analyses of low‐frequency noise. Koppen3 analyzed the optimized and selected project comprising four Vestas V112‐3.0 MW turbines with 119 meter hub height. A special analysis of low‐frequency noise in the selected project was made by Koppen4. Upon request from local residents, an additional analysis of low‐ frequency noise was made by Koppen5 taking into account information given in an article by Møller and Pedersen6 as well as new regulations of low‐frequency noise from wind turbines in Denmark7. Subsequently, the City Council of Maastricht has requested the present report in particular addressing certain questions. Unfortunately, only the latest Dutch report5 was made available in English, but employees of the City Council and Arcadis Nederland BV have been very helpful answering questions. In addition, we have used original noise measurements8 and data sheets9,10. The report is public and may be re‐distributed as a whole. 2 Introduction A brief introduction to low‐frequency sound is relevant. Sound and noise can be characterized by their frequency. The range from 20 Hz to 20 kHz (20 cycles per second to 20,000 cycles per second) is usually called the normal hearing range or the audio frequency range. Sound with frequencies above 20 kHz is denoted ultrasound and cannot be heard by humans. Sound with frequencies below 20 Hz is denoted infrasound. It is usually understood that also infrasound cannot be heard, but this is wrong.