What is a simultaneous interpreter? A simultaneous interpreter is - as you can tell by looking at the words - someone who interprets for someone in another language while the speaker speaks without interruption. This is the opposite of consecutive interpreting, because a consecutive interpreter awaits his turn and does not start speaking until the speaker allows him the time to do so. Simultaneous interpreting is one of the most common kinds of interpreting. But also the most difficult. 

When do you need an simultaneous interpreter?

You need a simultaneous interpreter when at least one person attending your event can not understand what the speaker says, due to the fact that he speaks a different language, and there is no time or opportunity to let the speaker pause regularly. Examples:

• You are holding a stockholders meeting in English, but several trustees or members of your board of management, and several stockholders, speak Chinese and could have difficulty with the English language. And perhaps you are expecting questions to be asked in Chinese which the English speaking people present should also understand. In that case it is best to use an interpreter booth, one or (preferably) more simultaneous interpreters, and a sound system with microphones for the interpreters, microphones for the speakers, and headsets for everyone.
• You are a marketing research company. You are going to have interviews with some respondents - in Chinese. But an English speaking representative of your foreign customer wants to listen in on several interview.In that case, you reserve an extra room for one or more simultaneous interpreters and your guest,,; put a video camera and at least one microphone in the interview room, and a sound/video system connected to it in the other room, with a set of headphones for the interpreter.
• You are organizing a symposium with Chinese speakers, but are expecting a number of English speaking visitors. In that case you hire one or more simultaneous interpreters, and a so-called whispering or guide set for the sound (microphone, infrared transmitter and headphone sets).กค      An English-speaking customer of your law firm sues one of his Chinese business relations. You hire one or more simultaneous interpreters and let them whisper a translation of the proceedings of the trial.กค      You are organizing a conference with both English-speaking and Chinese-speaking speakers and visitors. There will be speeches and discussions in both languages. You reserve a conference center or hall, an interpreter booth, microphones, headphones and... simultaneous interpreters. How many interpreters do you need? In the examples above you regularly need to hire more than one interpreter. But now you might ask: How do I determine whether I need one interpreter or more? In order to be able to find the answer, you need to know how a simultaneous interpreter works. It is really a very complex process, one that only very few interpreters can handle well. When a speaker speaker is speaking, and does not pause for interpretation, the interpreter must do the following:
•  listen to what the speaker is saying. translate it in his mind.  render the translation in his microphone.
• (and this is the most difficult part) at the same time listen to what is being said by the speaker while himself is speaking.

There are some solutions for this problem: Sometimes the event's program offers possibilities for regular breaks, perhaps because of visual presentations in -between the speeches. In that case it is not impossible that one interpreter will suffice. But if the speeches go on and on, you may expect the interpreter to get too tired after a while. In that case it can be necessary to hire more than one interpreter, so they can alternate. Or perhaps you can get another interpreter for different parts of the day - be creative. But whatever you do, do not underestimate the need for a solution for the interpreter's exhaustion problem, because a serious loss of concentration will result in a loss of quality in the translation. 

Whispering interpreters are simultaneous interpreters who whisper their translations. Usually they work under circumstances where the listeners are a minority as far as their language is concerned: it can be one person, or perhaps just a few. Is it one or two people, then the interpreter will usually work without sound equipment and he will literally whisper his translation to his listeners.

Conversation interpreters can be simultaneous interpreters, but not necessarily. In the above mentioned example of the marketing research company it is clear that a simultaneous interpreter is needed to translate the interviews. But is there time for people to pause during a conversation, and if there is no objection to having participants in the conversation wait for the translation each time a sentence is spoken, you may consider using a consecutive interpreter.

Court interpreters (legal interpreters) are usually simultaneous interpreters. The chance, however, that you will need a court interpreter, is rather slim - unless you work for a court. Since most courts already have a list of interpreters they work with, we will not explain their work here.

Conference interpreters are, in fact, always simultaneous interpreters. They generally work in interpreter's booths with electric transmission equipment.