The sound power level from a wind turbine is given by the manufacturer as 100 dB(A) in a wind speed of 5 m/s and 104 dB(A) in a wind speed of 10 m/s. What are the likely A-weighted sound pressure levels at 200 m and at 500 m for these two wind speeds? The hub of the turbine is at a height of 25 m, and the surrounding countryside is relatively flat. Is this noise likely to cause sleep interference inside a house?