Applies to laboratory standard microphones meeting the requirements of IEC 61094-1. The principles of the method are applicable to other types of microphones. In particular, microphones which fulfil the requirements of IEC 61094-1, when fitted with a special adaptor, may also be calibrated according to this standard when the adaptor is removed. Specifies a primary method of determining the free-field sensitivity so as to establish a reproducible and accurate basis for the measurement of sound pressure under free-field conditions. This publication supersedes IEC 60486.