Checklist for simultaneous interpretation equipment

The following text has been compiled by the Technical Group AIIC (Swiss) to respond to several enquiries and calls for advice from the Interpretation Services of International Organisations based in Geneva. When planning multilingual conferences in venues other than in their own facilities, the Organisations’ Conference Services may wish to check against these requirements that the interpretation equipment they will work with is up to standards, and that it will allow for a flawless running of the planned event. This text is intended to serve as practical technical guidelines for those responsible for the organisation of conferences. It has been approved by the AIIC TechNet and will be regularly updated, as needed.  

For further information please contact the members of the Technical Group  AIIC (Swiss):  

Evelyn Moggio-Ortiz:
or write directly to AIIC TechNet :

Interpretation at multilingual conferences  

From the technical point of view, a multilingual conference requires reliable interpretation equipment, operated by competent technicians. Here are some points to help you ensure that the equipment you will use is adequate to your needs.  The AIIC Technical Group will be pleased to discuss the details with you.  

I. Booths

In order to ascertain that the overall installations you plan to use correspond to your needs, make sure to obtain:

  • The general layout or floor plan of each meeting room, with details: seating capacity, windows, exits, light sources, rostrum location, etc.
  • The number and position of the built-in booths in each meeting room.
  • The number and position of mobile booths planned in each meeting room.  

a) Built-in Booths  

The full requirements for built-in SI booths are given in ISO Standard 2603:1998.  

Here is a reminder of its main provisions (quoted in brackets), plus a few tips drawn from interpreters’ experience.

  • Number of booths: Provide one booth per outgoing language.  
  • Dimensions of SI booths (4.5) : Booths should accommodate 2-3 interpreters seated in comfort. (see dimensions in ISO 2603)  
  • Visibility (4.6) : There should be large windows in front and on the sides for visibility into the other booths. Windows should start at the level of the working surface (table) and be at least 80 cm high. They should run the whole width of the booth.  There should be no vertical support in the center of the front window.  Windows should be made of non-reflecting glass. . Windows should be slightly tilted forward so as to avoid glare and reflections.  
  • Ventilation/air-conditioning/heating (4.9) : Booth air-supply systems should be controlled independently from those supplying the conference room and/or the rest of the building and should have a 100% fresh-air intake (no recycled air mixture).  Each booth should have an individual unit or individual thermostat controls. The fan should run silently, but not produce draughts.  
  • Insulation/soundproofing (4.8) : There should be no interfering noise from other booths nor from the conference room.   
  • Adequate Work area (5.4) : There should be a table running the entire width of the booth and deep enough to accommodate the SI equipment, plus papers, reference books, a glass of water for each interpreter and other materials needed by the interpreters.  
  • Document storage (5.4) : Shelves or pigeonholes on one side or rear walls (but not beneath the table) are desirable - or even an extra table. A 2-tier trolley can be very useful, or a shelf above the front window (depending on booth design - but watch head clearance when standing up).  
  • Lighting (5.2)  : Table lamps with dimmer are essential for interpreters to read texts or take notes when the room lights are off. Overhead fluorescent tubes are not suitable, because of interference (crackling) with the SI equipment. In selecting table lamps, beware of: 1) obstructing the view, 2) heat generation, 3) glare into the next booth and/or conference room. Beware of cheap dimmers whose rheostats may interfere with SI equipment, causing crackle.  
  • Seating (5.5) : Adjustable, silently operated chairs on 5 casters are the ideal. Whenever possible, provide footrests as well.  
  • Booth location (4) : Booths should be located at the rear of the room, facing the rostrum/screen. The distance from booths to rostrum or projection screen should not be over 30 m (20-25 is preferable). Otherwise, interpreters may find it difficult to read figures and graphs. If the booths-to-rostrum distance is more than 30 m, TV monitors need to be installed inside the interpreter booths. This requires cameramen filming the proceedings (at least rostrum and speaker) with constant attention to what is happening in the room. If not at the rear, at the side and towards the rear of the room. The minimum angle sideways at which a screen can be read is 30-35 degrees. In this case, the booths should be built (or placed if mobile) in a fish-bone formation, each booth slanted at an angle offering the best view of the rostrum and screen.  In a separate soundproof area, so that individual booths do not open onto a public space. Background noise disturbs the working interpreters; it is also picked-up by their microphones and relayed into the listeners’ headsets.  
  • Booth level (4.1) : If the room floor is flat: The booth floor should be about 1 m above floor level (no more!). In a small room it can be less, provided the interpreter can see across the room clear of delegates’ heads. If located any higher than 1.5 m above the room floor level, the viewing angle into the room becomes too steep and part of the audience will disappear from view.  In a large tiered hall: A booth position half-way up from the rostrum, along the side of the room, is likely to be more satisfactory than behind the last row of seats.  
  • Access and exits (4.4, 6) : Access to booths should be: Independent, and not through the conference room; Free of hazards (easy and unencumbered, wide enough passage, no spiral or awkward stairs, properly lit, no wires or cables in the way, etc.). Getting from booths to the conference room should be handy, to facilitate document availability and contact with the meeting.  Booths should have easy access to fire-escapes. Floor-covering in access passages and booths should be sound-absorbent and not hollow, to avoid disturbing resonance effects.   
  • Communication with technicians (4.2.2, 9.9, 9.10) : A qualified technician should be present at all times throughout the meetings; hence a booth with console must be provided for him/her in every meeting room. The technician should:  - Have a clear view of the conference room and screen. - Be visible from the booths and viceversa. - Have quick access to the booths.   

b) Mobile Booths  

The full requirements for mobile SI booths are given in ISO Standard 4043:1998.  

Here is a reminder of the main provisions, plus a few tips drawn from interpreters’ experience  

  • Number of booths : Provide one booth per outgoing language.  
  • Dimensions of mobile SI booths (4.4) : Booths should accommodate 2 to 3 interpreters seated in comfort: (1,60 to 2,40 m wide, 2 m high and 1,60 m deep). Occupants should be able to enter and leave without disturbing one another.  
  • Adequate work area (8) : The working surface shall extend the full width of the booth and with a depth of at least 45 cm, to accomodate interpreters consoles, microphones, lamps, documents, drinking glasses and writing gear easily. Nearby shelves or side tables should be supplied for ready access to documents needed during a meeting, but which cannot be kept in the booth due to lack of space.  
  • Ventilation (7) : Mobile booths are often smaller than permanent booths. An adequate supply of fresh air is a main concern. As booths have to be kept closed during a meeting’s proceedings, the general ventilation/air conditionning of the meeting room is not sufficient to ensure proper air supply in the booths.   Each booth should have a silent-running fan in the ceiling and air inlets at the bottom of the front wall and outlets at the top of the back wall. The fan should be big enough to ensure proper air turnover, but not produce draughts.  
  • Insulation/soundproofing (6, 4.5) : There should be no interfering sound from other booths nor from the conference room.  Soundproofing can be achieved with 1 cm thick carpet or foam-rubber insulating cover on walls.  Booths should have doors (not curtains), at the back that open outwards, easily and quietly  
  • Visibility (5) : There should be windows at the front and sides, providing a clear view around the conference room, as well as into the other booths.  Windows should be 80 cm high. There should be one single window across the whole front of the booth. The side windows should be 80 cm wide. .No vertical support in the center of the front window.  Windows should be made of non-reflecting glass.  
  • Lighting (8) : Table lamps with dimmers are essential for interpreters to read texts or take notes when the room lights are off. Care should be taken in selecting lamps that do not: 1) obstruct the view out of the booth; 2) generate too much heat;  3) cause glare into the next booth and/or the conference room; and 4) take up too much of the available work-space. Cheap dimmers whose rheostats may interfere with SI equipment should be avoided. 
  • Seating (10) : Chairs should be adjustable and easy to move about (silently). Permeable materials are preferred. Whenever possible, provide also footrests.  
  • Booth location (4.3) : A sufficiently large area shall be provided to place the booths together in a position from which the rostrum, participants, blackboard and projection screen can be fully seen, i.e. along the side, towards the back of the room.  If the shape or size of the room prevents placing the booths at the back with a direct view to the rostrum, they should be placed on the side but in fish-bone formation, so that each booth is slanted at an angle allowing the best possible view of the rostrum and screens. Booths should be placed on the opposite side from any screens, not the same side, so that interpreters can see screens clearly. Booths should be set up on a raised platform (25-30 cm high) so as to afford interpreters a clear view of the whole room and participants. The platform must be stable, carpeted or suitably sound-absorbent and of safe and easy access.  Booths should not open onto a public space. Background noise disturbs the working interpreters; it is also picked-up by their microphones and relayed into the listeners’ headsets.   

II. The S.I. system

As a rule, your equipment supplier should provide the whole system, including, SI control panels, microphones, amplifiers and headsets (and, if needed, mobile booths)*.   The equipment supplier’s technician should operate the system throughout the conference, and not leave it in the hands of untrained operators.  Ensure that the booths meet ISO standards as regards size, ventilation and lighting and are positioned in such a way that interpreters can see the rostrum and the screen used during the meeting.  Make sure to have the right number of booths, that is, one booth per output language.  Two-way booths (working into two languages, such as the Chinese and Arabic booths) should be equiped with 3 consoles and the correct outgoing channels.  

* Note: The standard hotel microphone and amplifier system (PA system) should not be used as it is incompatible with the simultaneous interpretation equipment and cannot be operated by the SI equipment technician. Hotel microphones do not have a button for the delegate to switch on or off, nor can the chairman of the meeting cut them off. The most frequent and annoying disruptions of meetings in hotels are caused by malfunctioning hotel microphones.  

Checking the SI equipment

Before the meeting opens, ask the consultant interpreter or team leader to check with the chief technician that the equipment is working properly. Have each microphone checked, with interpreters in each of the booths. Also check the delegates’ receivers in different parts of the room. This is essential to ensure that the meeting starts without technical hiccups.  

The equipment supplier must provide a sufficient number of microphones and receivers (headphones) for all speakers and delegates. All microphones should be monitored from the central console operated by the technician. This is only possible if the microphones are part of the equipment provided by the SI equipment provider.    

III. The importance of sound

Good sound quality in the booth and in the conference hall is an essential factor in simultaneous interpretation. Poor sound causes unnecessary stress and fatigue, both to delegates and to interpreters.  Good sound depends on many factors, such as: - proper sound equipment that supplies the full range of sound: 125-12,500 Hz; - good dedicated conference microphones; - good-quality, lightweight earphones; - adequate room acoustics.

Acoustic feedback and echoes in the meeting rooms may impair simultaneous interpretation. Moreover, a large number of delegates depend on headset reception which may be rendered inaudible by loudspeakers. Therefore, public address systems should not be operated in combination with simultaneous interpretation.  

  • The interpreter’s control panel (8, 9): The consoles or control panels should satisfy the following conditions :  - All controls should operate silently; - The “listening” and “speaking” controls should be clearly differentiated (e.g., microphone on/off, tone control, incoming and outgoing channel selection, etc.) ; 
  • Channels : Separate incoming and outgoing channels. Selectors for outgoing and incoming channels. One outgoing channel per language, plus one channel for the floor language 
  • Other : Tone controls to adjust bass and treble settings.  An automatic, relay pre-selection switch is recommended and is obligatory in two-way booths.  A “cough button” (mute button).  
  • Microphones :Supply one individual microphone for each interpreter.  For audio-visual presentations (slides, transparencies, Powerpoint), the speaker must have a lapel or neck microphone to enable her/him to move away from the rostrum and still be heard through the system.  
  • Earphones (10):  An individual set of earphones must be provided for each interpreter. Earphones must be high-quality and lightweight, designed specially for interpreters and provide dry sound in the range of 125-12,500 Hz.  For headphone cables, the requirement is to leave 1.5 m of free cord, although the interpreter should be able to reach the document shelves easily, without having to remove the headphones.  
  • And more…  Infrared and fully cabled systems are the systems of choice. It is wise to provide for more channels than the number of built-in booths. Extra channels can be useful to accommodate additional languages working from mobile booths.  All cables running in and out of the booths, as well as on the platform leading to the booths should be protected, hidden and secured, and not represent a risk for interpreters or others moving in that area.   

IV. Further hints to facilitate the task of interpreters  

  • Documents: Make sure that interpreters receive the relevant conference documents as early as possible. In addition to the conference agenda and any written speeches, supply interpreters with curricula vitae of key speakers, the names of the officers of the Organisation, minutes of previous meetings on the same subject, as well as other useful background information. A set of the Organisation’s Basic Texts should be placed in every booth. When documents are circulated during a meeting, make sure that interpreters obtain a copy before they are discussed. Each booth should receive at least one copy of such papers, if possible in all conference languages.  
  • Briefings: Before any technical conference, organise a briefing session with the interpreters and the key speakers at the meeting and/or an expert officer of the Organisation. Interpreters should be able to ask questions on contents, terminology and procedure.  
  • Presentations:  If slides or transparencies are to be shown and require interpretation, make sure that the screen is clearly visible from the booths and that interpreters receive a script or a copy of the texts and pictures to be projected in good time. Anticipate speakers moving away from the rostrum while speaking: provide the speaker with a lapel or neck microphone.  
  • Films:  If films are to be shown and require interpretation, the interpreters must receive a copy of the script beforehand. For the dialogues to be interpreted, the film’s sound-track must be directly fed from the projector into the interpreters’ earphones, i.e. not through microphones in the room.  
  • Liaison:  It is advisable to appoint one interpreter per meeting as team leader; such a person will guarantee a smooth coordination within the team, and liaise at all times between the interpretation coordinating officer and the interpreters. Conference interpreting is team work; it would therefore be appropriate to introduce the interpreters to your staff and to the technician before the meeting.  
  • Interpreters’ room:  Provide an office or rest area, where interpreters can collect documents, check the assignments schedule, study conference papers when they are not in the booth and where messages can be left for them.  
  • Water:  Fresh drinking (bottled) water should be made available to interpreters, either in the booths or readily accessible nearby. A glass for each interpreter should be placed in the booths. Glasses should be changed after every session.  
  • Disposal bins:  Appropriate bins must be placed inside or near the booths to allow for the disposal of obsolete documents.  
  • Rest-rooms: There should be toilets close to the booth area.   

Technical Group AIIC (Swiss) Geneva, December 3, 2004     
Copyright © 1992-2005 AIIC. All rights reserved.   

Recommended citation format:
AIIC. "Checklist for simultaneous interpretation equipment". May 16, 2007. Accessed May 27, 2020. <>.

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