IEC 60268-4:2010(E) specifies methods of measurement for the electrical impedance, sensitivity, directional response pattern, dynamic range and external influences of sound system microphones, and also details the characteristics to be specified by the manufacturer. It applies to sound system microphones for all applications for speech and music. It does not apply to measurement microphones, but it does apply to each audio channel of microphones having more than one channel, for example for stereo or similar use. It is also applicable to flush-mounted microphones and to the analogue characteristics of microphones with digital audio output. For the purposes of this International Standard, a microphone includes all such devices as transformers, pre-amplifiers, or other elements that form an integral part of the microphone, up to the output terminals specified by the manufacturer. This fourth edition cancels and replaces the third edition published in 2004, and constitutes a technical revision. The main changes with respect to the previous edition are the following: - correction of noise measurement, - added annex for digital microphones, - added requirement for tolerances in data to be specified.