Simultaneous interpreters are skilled in listening and speaking at the same time, delivering the interpreted speech a few seconds after the original speaker. A simultaneous interpreter must first quickly listen to the speech to understand the true meaning of the message the speaker is trying to convey. This is much more difficult than it sounds, especially considering both the time and often physical constraints of simultaneous interpreting.
Simultaneous interpreting is often used for larger meetings with multiple speakers and audience members. The flow of communication is achieved through the use of such technology as microphones, earpieces, and soundproof booths. Due to the spatial limitations of most facilities, the interpreter(s) cannot see the speaker as they are delivering their speech. This provides some difficulties, as even with video monitoring equipment, the interpreter(s) cannot pick up subtle nuances in the speaker's tone and mannerisms.
Simultaneous mode of interpreting is mentally taxing and requires a high level of concentration, necessitating two simultaneous interpreters of comparable skill. The average length of time an experienced simultaneous interpreter can interpret for is approximately 20 minutes. The second simultaneous interpreter, listening/watching the speech on audiovisual equipment, would then step into alternate with the first simultaneous interpreter to ensure seamless interpretation.