Simultaneous Interpreting

In (extempore) simultaneous interpretation (SI), the interpreter renders the message in the target-language as quickly as he or she can formulate it from the source language, while the source-language speaker continuously speaks; an oral-language SI interpreter, sitting in a sound-proof booth, speaks into a microphone, while clearly seeing and hearing the source-language speaker via earphones. The simultaneous interpretation is rendered to the target-language listeners via their earphones. Moreover, SI is the common mode used by sign language interpreters, although the person using the source language, the interpreter and the target language recipient (since either the hearing person or the deaf person may be delivering the message) must necessarily be in close proximity.

The first introduction and employment of extempore simultaneous interpretation was the Nuremberg Trials, with four official working languages.