This part of IEC 61400 presents measurement procedures that enable noise emissions of a
wind turbine to be characterised. This involves using measurement methods appropriate to
noise emission assessment at locations close to the machine, in order to avoid errors due to
sound propagation, but far away enough to allow for the finite source size. The procedures
described are different in some respects from those that would be adopted for noise
assessment in community noise studies. They are intended to facilitate characterisation of
wind turbine noise with respect to a range of wind speeds and directions. Standardisation of
measurement procedures will also facilitate comparisons between different wind turbines.
The procedures present methodologies that will enable the noise emissions of a single wind
turbine to be characterised in a consistent and accurate manner. These procedures include
the following:
• location of acoustic measurement positions;
• requirements for the acquisition of acoustic, meteorological, and associated wind turbine
operational data;
• analysis of the data obtained and the content for the data report; and
• definition of specific acoustic emission parameters, and associated descriptors which are
used for making environmental assessments.
This International Standard is not restricted to wind turbines of a particular size or type. The
procedures described in this standard allow for the thorough description of the noise emission
from a wind turbine. A method for small wind turbines is described in Annex F.