Different interpreting techniques

Simultaneous interpretation

Interpreting while the delegate is speaking.
The interpreter works in a soundproofed booth with at least one colleague. The speaker in the meeting room speaks into a microphone, the interpreter receives the sound through a headset and renders the message into a microphone almost simultaneously. The delegate in the meeting room wears a headset and selects the relevant channel on the receiver to hear the interpretation in the language of his/her choice.

Consecutive

Interpreting after the speaker has finished.
The interpreter sits with the delegates, listens to the speech and renders it, at the end, in a different language, generally with the aid of notes. In the modern world consecutive interpreting has been largely replaced by simultaneous, but it remains relevant for certain kinds of meetings
(e.g. highly technical meetings, working lunches, small groups, field trips).

Well-trained interpreters can render speeches of 10 minutes or more with great accuracy.

Whispered Simultaneous Interpreting (chuchotage).

The interpreter is seated or standing among the delegates and interprets simultaneously directly into the ear of the delegates.
Nowadays, the whispering interpreter will often use ‘tour guide equipment’, consisting of a wireless microphone and headphones for the participants. In this way, more participants can benefit from the interpretation. This technique is used mainly in bilateral meetings or in groups where only a few delegates do not share a common language. Whispering is often used instead of consecutive in order to save time.

Source: European Commission, SCIC