IEC 914-1988,Conference systems-Electrical and audio requirements.
IEC 914 applies to conference systems and to the parts of which they are composed or which are used as auxiliaries to such systems.
4. Persons
4.1 Delegate
A person participating in a conference having the facilities of a conference system to speak and listen.
4.2 Interpreter
A person who interprets a spoken language into one or more other languages via the interpretation system.
4.3 Operator
A person operating the control equipment and the audiovisual equipment, changing tapes on tape recorders and monitoring quality of sound to the interpreters and delegates.
4.4 Technician
A person who can perform the functions of an operator and is in addition trained in the diagnosis and repair of equipment faults.
4.5 Audience
Persons not actively participating in the conference, having only the facility for listening.
5. Earphones
5.1 Earphone (IEV 801-07-18)
Electroacoustic transducer by which acoustic oscillations arc obtained from electric signals and intended to be closely coupled acoustically to the ear.
5.2 Headphone (IEV 801-07-20)
Assembly of one or two earphones on a headband.
5.3 Headset (IEV 801-07-21)
Assembly of a microphone and one or two earphones on a headband.
5.4 Insert earphone (IEV 801-07-22)
Small earphone that fits either in the outer car or is attached directly to a connecting element, for example earmould inserted into the ear canal.
5.5 Supra-aural earphone (IEV 80 1-07-23)
Earphone applied externally to the outer ear.Now you can download IEC 914 pdf.