IEC 61842 pdf download Microphones and earphones for speech communications 1 Scope This standard applies to the microphone part and earphone part of handsets，headsets orearsets for speech communications,and also to the microphone units and earphone units ofbuilt-in handsets,headsets or earsets.The object of this standard is to establish definitionsrelating to these electroacoustic transducers，and to standardize the characteristics to bespecified and the...