Microphones and earphones for speech communications Ingestion-build-264231 forging stock and forgings

forging stock and forgings

1 Valve seat leak test

Fire-stopping

Paints and varnishes  - Cross-cut test

Microphones and earphones for speech communications Ingestion-build-264231 forging stock and forgings1 Scope This standard applies to the microphone part and earphone part of handsets, headsets or earsets for speech communications, and also to the microphone units and earphone units of built in handsets, headsets or earsets. The object of this standard is to establish definitions relating to these electroacoustic transducers, and to standardize the characteristics to be specified and the relevant methods of measurement. This does not exclude the use