There are two types of conference interpreting:  consecutive and simultaneous.

• In consecutive interpreting, the interpreter listens to the speaker, takes notes and renders the speech in the target language once the speaker has finished.

• In simultaneous interpreting, the interpreter sits in a booth overlooking the meeting room.  The speeches given are interpreted simultaneously and relayed to delegates by means of the sound equipment

   

Although most people think of the Nuremburg Trials after World War II as the birth of simultaneous interpretation (English, French, Russian, and German), in fact, the concept of simultaneous interpretation was born in the US and existed for some time before there was any large-scale demand for it. 

As early as 1924, Edward Filene, the Boston capitalist and social reformer, sponsored the use of simultaneous interpretation during entire official meetings of the International Labor Organization, and for more languages than the four used in Nuremberg.  His goal was to find an alternative to consecutive conference interpretation.  

The Nuremberg Trials, although not the first example of simultaneous interpretation, did have radical consequences for the profession.

At that time, consecutive interpretation, which had been in use since the 1919 Paris Peace Conference, was the standard at international gatherings, such as at meetings of the League of Nations in Geneva, where English and French were used.

The Nuremberg trials changed all that. 

• complete mastery of the active (target) language(s), i.e. the language(s) into which the interpreter works;
• in-depth knowledge of the passive (source) languages, i.e. languages from which the interpreter works;
• university degree or equivalent;
• sound general knowledge and understanding of current affairs.

• ability to analyze and construe facts; intuition;
• speed of reaction and ability to adapt without delay to speakers, situations and subjects;
• powers of concentration;
• above average physical and nervous staying-power;
• pleasant voice and public-speaking skills;
• high degree of intellectual curiosity;
• intellectual integrity;
• tact and diplomacy.

• complete mastery of the active language(s) is essential if the original speech is to be reproduced in the target language with all its nuances, whatever the subject, level of technical complexity and style. This implies a broad vocabulary base as well as the ability to express oneself accurately and with ease in a variety of registers.
• in-depth knowledge of the passive languages will, for example, enable an interpreter to understand the English of an American, a Japanese or an African. In both the active and passive languages, an interpreter must be able to draw on a large number of synonyms, idiomatic expressions, proverbs and quotations.
• university degree or equivalent: the intellectual training and maturity acquired by a university education is the best way of preparing for interpreting as a profession. A language degree is not necessarily the best training for interpretation. Degrees in law, economics, etc. are useful provided that the candidate knows her/his working languages well enough. Interpreting techniques per se can be acquired later. But only those candidates with the required aptitudes are likely to benefit from formal training in interpreting.
• the ability to analyze information and construe meaning; intuition are essential. When interpreters work, they have to analyze everything that they are hearing, and to internalize it so that they can re-express what they have understood for the listeners in another language and another culture. This means that the ability to analyze information and construe meaning, as well as using their intuition to anticipate what the speaker is going to say, is invaluable.
• speed of reaction and ability to adapt without delay to speakers, situations and subjects. When recruited for a conference, the interpreter often has only limited time in which to prepare for the meeting, with or without documents. This means that the essentials of the subject, very often a previously unfamiliar one, have to be grasped rapidly, including the technical terms, so that they can be used appropriately. Each new speaker may be an unknown quantity to the interpreter who consequently has each time to adapt instantaneously to a different accent, to the pace and style of each individual.
• powers of concentration. The very high level of concentration required to perform the operations involved in simultaneous interpretation has to be kept constant. A lapse in concentration and both the interpreter as well as those listening to the interpreter may lose the thread of the argument. The interpreter must be able to sustain this high level of concentration for about half an hour before a colleague takes over. In simultaneous interpretation there are always at least two interpreters per booth. Staying power is certainly something that can be increased with practice, but it should be an initial quality to be looked for in the prospective interpreter.
• pleasant voice and public-speaking skills. An interpreter must be a clear and lively speaker and despite working under pressure, an interpreter's delivery must remain smooth and the voice pleasant so as to prevent the listeners' attention from slackening.
• the interpreter's high degree of intellectual curiosity means that s/he will be able to follow the participants without difficulty, particularly references to current economic, political or social affairs. Thanks to extensive general knowledge, the interpreter will be able to place a speaker's utterance in its general context.
• under no circumstances does the interpreter depart from the strictest intellectual integrity.
• lastly, an interpreter needs tact and diplomacy to deal with difficult situations (misunderstandings, tension) and to know how to behave in relation to the delegates, regardless of their attitude towards the interpreter.

These qualities are not exercised independently of one another as and when needed, but come together to constitute a whole, i.e. a professional interpretation. A genuine interpreter identifies closely with the speaker and while interpreting will adopt the speaker's point of view.

This is particularly apparent in consecutive interpretation but whatever the mode of interpretation, an interpreter's finest reward is to see the audience laughing at the witticisms of the original, albeit in another language, responding to the rhetorical effects of the speaker, nodding in agreement or shaking their heads in disagreement, in other words acting as though the speaker and the interpreter were one and the same person.

All this brings us to the heart of the matter. If one believes that one has all the qualities mentioned in the foregoing pages, how does one become a conference interpreter?

There are a large number of courses and schools around the world which offer young people who have completed their secondary school studies a course of language studies to become "translator-interpreters".

Much of the syllabus is in fact taken up with language learning, taught in a more accessible way than in a conventional academic setting.  Additionally, the syllabus usually includes a number of more general courses (economics, history, politics, sociology, etc.) which extend the students' general knowledge and prepare them for careers in a number of areas, e.g. executive secretaries, public relations, travel industry, teaching, journalism, translation, and sometimes conference interpreting.

However, as early as 1970, at a symposium organized by UNESCO, organizations in the UN system arrived at the conclusion that "the training programs that best meet the needs of the major employers of interpreters are those which seek, in a relatively short period of time, to teach postgraduate students already possessing the requisite language skills, the techniques of translation and interpretation".

This reflects two postulates which have always been fundamental to the stance taken by the International Association of Conference Interpreters (AIIC):

• candidates to interpreter training courses must have achieved the requisite level of language competence in all their working languages before being admitted to training;
• interpreter training shall be at least at undergraduate but preferably at postgraduate level.

Additionally, in order that trainees actually hear their various languages being used, it is recommended that training courses admit students having a variety of mother tongues.