How does a Simultaneous Interpretation system work?

Here's an example...

The sound from the presenters'/speakers' voice is picked up by various microphones (1) in the room, processed into the control unit (2), and the microphone control (3).

The signal from those microphones is then sent to the interpretation booth (4), so the interpreters can hear, through headphones, what needs to be interpreted. This same signal is also sent to a sound system in the room, for the audience to hear the speaker directly in the room.

The interpreters' voices are sent from the soundproof booth through their interpreter's console microphone (5) to InfraRed Transmitters (6), or FM transmitters, which then broadcast the signal throughout the room via either Infrared Radiators (7), or antennas (for FM systems) for the delegates to hear, through their respective receiver/headphones (8)

What's the difference between an Infrared system (IR) and a Radio Frequency (FM) system?

There are two different ways of broadcasting the interpretation signal out into the conference room for the delegates to hear through their receivers:

1. Via an Infrared (IR) light-emitting transmitter, which enables the signal to be heard only within the room it is being broadcast; since light waves transmitting the signal, these light waves are therefore confined to the room in which they are being sent. Only special Infrared receivers can pick up the signal, making it a very private and secure system to use for sensitive information discussions and meetings.

2. With a Radio Frequency (RF) system, the interpretation signal is sent via radio frequencies, which can go through walls; therefore the signal can be heard outside the room, given the very nature of radio frequency systems. The signal can be picked up with special Radio Frequency receivers, even outside the room, making it a convenient system for meetings where delegates can be outside the conference room, and are still able to pick up the signal from inside the conference room.