The calculation of wind turbine noise is described by the standard ISO 9613-2.
This shows that the turbine noise output will reduce due to the following factors:
• Air absorption
• Ground absorption
Turbine noise increases as wind speed increases, but background noise increases more,
which helps to mask the noise.
The noise produced by a wind turbine at different wind speeds is specified, and guaranteed,
by its manufacturer.
Using the methodology defined by the ISO 9613-2 the noise at a given distance from
the turbine can be calculated.
Through our membership of the Institute of Acousticswe are very familiar with the
current guidelines, as defined by “The assessment and rating of wind farm noise”
ETSU- R-97 and the IOA Good Practice Guide are that the noise levels at a residence
should ideally be below 35 dB(A) during amenity times (evenings and most of the weekend)
and 43 dB(A) at night. The night time level assumes that the occupant will be indoors
and the noise will be reduced by at least 10 dB by the windows, even if they are
open for ventilation.
If the turbine noise is predicted to exceed the above levels then it is necessary
to monitor background noise levels and to show that these will be within 5 dB of
the maximum noise that the turbines will make.
FOR INFORMATION ON THE COLLECTION OF BACKGROUND NOISE DATA CLICK HERE