This part of IEC 61400-11 presents measurement procedures, that enable the sound characteristics of a wind turbine to be determined at receptor (immission) locations. This involves using measurement methods appropriate to sound immission assessment at far-field locations of a wind turbine or wind farm. The procedures described are different in some respects from those that would be used for noise assessment from other industrial sound sources in environmental noise impact assessments. They are intended to facilitate characterization of wind turbine sound with respect to a range of wind speeds and directions.

The procedures present methodologies that will enable the sound immission and sound characteristics of wind turbines to be described in a consistent and accurate manner. These procedures include the following aspects:
• location of acoustic measurement positions (receptor position);
• 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 parameters, and associated descriptors which are used for making environmental assessments.

This document is not restricted to wind turbines of a particular size or type. The procedures described in this document allow for the thorough description of the sound characteristics and sound immissions from wind turbines.