How Does Simultaneous Interpreting Equipment Work?

This post is a general explanation about simultaneous interpretation equipment for end users.


What is Simultaneous Interpreting:

Simultaneous interpreting (or simultaneous interpretation) is one of the most complex types of language use. Interpreters are using highly specialized wireless equipment and are working in a soundproof cabin called “simultaneous interpreting booth.”


Get Started with InterStar


Brief History of Simultaneous Interpreting Equipment:

Attempts to design simultaneous interpreting equipment started in the 1920s with Edward Filene and Alan Gordon Finlay. The system was called “the Filene-Finlay simultaneous translator” and was used to read texts that had already been translated before the event.

alan gordon finlay

Alan Gordon Finlay, inventor of an early simultaneous interpretation system. Photo taken cir. 1920.

No one thought at that time that “live” simultaneous interpretation was possible.

During the Nuremburg Trials after WWII we see simultaneous interpreting equipment that is more similar to what we have today.

A lot of credit in perfecting the equipment goes to the United Nations, where simultaneous interpretation was introduced (with some resistance at first) after the World War II.


Simultaneous Interpreting Equipment Today:

Today the majority of conferences is in simultaneous interpretation mode, and manufacturers of simultaneous interpretation equipment abound.

A note has to be made that like in any market quality of design and construction varies greatly and – caveat emptor – cheap solutions are not too reliable.

quality interpretation servicesUtmost care has to be taken when selecting your simultaneous interpretation equipment provider: best if it is a company that specializes in such equipment and not just an audiovisual company or a videographer.

Professional conference interpretation and translation agencies will either have their own equipment or have a working relationship with such specialized companies.

It is best if you purchase conference interpreter services and rent simultaneous interpretation equipment from the same company instead of shopping around. It is one of the scenarios where one stop shopping for language services works!


 What Simultaneous interpretation Equipment Setups Exist?

Generally only 3:

Permanent installations

United nations HQThese are simultaneous interpretation systems permanently built into conference facilities – think the United Nations, the European Parliament or a major conference center.

Booths are actually small rooms with doors where interpreters work. It is the most comfortable and convenient setup, but, for obvious reasons, it is not very mobile.

Portable/mobile setups

Most hotels and other venues do not have permanent installations. Instead, portable (mobile) booths have to be brought in and installed before the conference.

It must always be booths for at least 2 interpreters per booth per language and at some major conferences 3 interpreters per booth per language are engaged.

Portable booths have the same features as stationary ones such as lighting and ventilation, but the equipment is highly mobile.

Whispering Equipment:

It is a portable set consisting of a wireless handheld transmitter and standard wireless receivers. While good for tours or if the participants must move around a lot, it is not suitable for a standard conference in one room.    


What equipment is inside the simultaneous interpretation booth?

Simultaneous Interpreter Console

simultaneous interpretation equipment

Simultaneous interpretation console with a gooseneck microphone.

Simultaneous interpreter console is an electronic box with audio connections for the interpreter headset and the interpreter microphone. Because more than one interpreter is engaged, there must be as many headsets and microphones as there are interpreters.

The console has a number of switches to switch between languages, adjust headset volume and bass/treble, as well as turn the microphone off temporarily (mute button of cough cut.)  

Interpreter Headset:

Each interpreter must have his own her own headset provided to them by the audio technician.

tabletop microphones

Tabletop Microphones

Many professional conference interpreters own their headsets they travel with, and headset manufacturers have headset models specifically designed for best voice reproduction and for simultaneous interpretation.

Headsets must be binaural i.e. the interpreter must be able to hear the original speech with both ears.

Interpreter Microphones:

There are 3 major options for interpreter microphones:

Integrated into a headset. The microphone is attached to the headset with a special flexible gooseneck arm. It is the best and the most convenient option. When moving your head, the distance between the interpreter mouth and the microphone does not change.

An interpreter microphone integrated into a console.

It is a less convenient but still very legitimate option. The top surface of the interpreter console has a dedicated microphone connector (usually XLR) the gooseneck microphone is inserted into.          

Standalone tabletop microphone.

It is the least convenient option. A separate microphone in placed on the interpreter desk and connected to the console with a cable.

The danger here is that the interpreter may accidentally move the microphone when it is “hot” i.e. when it is on. The resulting sound may be very unpleasant for the delegates to hear.

In terms of microphone safety, headset microphones are certainly best!  

Other equipment in the Booth:

Other equipment in a simultaneous interpretation booth must include appropriate lighting, ventilation fans, chairs and may also include internet and power connections.

Wireless receivers for delegates:

simultaneous interpretation receivers

Wireless receivers for simultaneous interpretation

The audio feed from the speakers’ microphones is transmitted into interpreters’ headsets. The simultaneous interpretation interpreters produce is fed into a wireless transmitter and into receivers and headsets each delegate has.

A few points to remember:

-Always get your receivers and headsets before a conference starts, otherwise, you may have to do it in the middle of a presentation.

-For large conferences some conference organizers will issue you a receiver only in exchange for your identification document they will keep for the duration of the day or of the conference. Have an alternative form of ID on you in case if you need to use it during the event.

-When you turn on your headset for the first time, never use the full volume. While simultaneous interpreters are professionals and know how to use microphones, accidents happen and loud sounds may damage your hearing.  

-Same is true for interpreters. You must never tap or bang a live microphone – it is a serious health hazard for those who are listening to you i.e. for the conference interpreters.

-Know what channel your languages are on. Usually channels are numbered and the channel allocation will either be posted on simultaneous interpretation booths or announced before the conference.   

-A fully charged receiver should be operational without any issues for an entire day but sometimes batteries in simultaneous interpretation receivers discharge and sound quality deteriorates. Report it to the audio technican who will give you a new receiver.

 -To prevent microphone feedback never place your headphones next to a live microphone.      


Are there standards for simultaneous interpretation equipment?

Yes and they are rather detailed.

Standards are important for language translation and interpretation services.

ISO 2603 “Simultaneous interpreting – Permanent booths – Requirements” covers the built-in installations, and ISO 4043 “Simultaneous interpreting – Mobile booths – Requirements” covers portable equipment.

There are other guidelines and standards by other bodies, such as  ISO/FDIS 20109 “Simultaneous interpreting — Equipment – Requirements” or ASTM F2089: Standard Guide for Language Interpreting Services.

If you are interested in this topic, see the Further Reading section at the bottom of this page.  


Who is the best simultaneous equipment manufacturer?

While there are many manufacturers, we think that Bosch interpreter consoles remain the Golden Standard. Various knockoff consoles exist but they do not seem to provide good user experience for interpreters in terms of user friendliness and sound quality.     


Using the highest quality interpretation equipment is in your best interests as an end user. Critical applications such as simultaneous interpretation require professional grade audio equipment and trained technicians too.        


Further reading and sources:

Does ISO 9001 Certification Mean Better Quality from a Translation Agency?

All about Simultaneous Interpretation – FAQ

Guidelines for Organizers, Participants and Chairs of Bilingual and Multilingual Meetings

Client Provided Simultaneous Interpretation Equipment (based on AIIC recommendations and common practices).


Off Site Links:


Alan Gordon Finlay and the Telephonic Interpretation System

On Comintern and Hush-a-Phone: Early history of simultaneous interpretation equipment

Speakers, mind your microphone manners