Infrared systems

Audio transmission using infrared (an electromagnetic wave with a wavelength fa between visible light and radio waves) is often used in simultaneous interpretation and assistive listening systems. The main difference from radio transmission is that a signal transmitted in this way can only be received if the transmitter and receiver can ‘see’ each other (even if it is visibility through reflection from the surface of a wall). This is an important advantage - because systems installed in adjacent rooms do not interfere with each other. 

For the user, the operation of an IR system is no different to FM - they have a receiver and headphones (or an induction loop) connected to it, choose the audio channel they want to listen to and use the system - the receiver should not be hidden in a pocket or under a table to receive the signal. Bodypack receivers and a set of accessories are available - chargers, cases, lanyards, headphones and induction loops.