Inaudible noise of wind turbines  

Author:  Ceranna, Lars; Hartmann, Gernot; and Henger, Manfred

• Number of wind turbines and their size are constantly growing
• Wind turbines and wind farms generate strong infrasonic noise which is characterized by their blade-passing harmonics (monochromatic signals)
• Generated noise of wind turbines can theoretically be estimated
  • geometrical spreading ≈ R⁻¹
  • SPL ≈ rpm⁴
• Recordings from field measurements near a single wind turbine show that the theoretical model is also valid for frequencies below a few Hz
• Minimum distance between an infrasound array and a wind farm can be estimated to avoid reduction of the array’s detection capability (e.g. 600MW wind turbine: d >15 km, 11-element wind farm: d >30 km)

Presented at the Infrasound Workshop, November 28 – December 02, 2005, Tahiti
Lars Ceranna, Gernot Hartmann, and Manfred Henger
Federal Institute for Geosciences and Natural Resources (BGR), Section B3.11, Stilleweg 2, 30655 Hannover, Germany

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