The Lord Chancellor’s department recommends infrared hearing systems for use in courts due to the security aspect. The signal cannot be heard outside the room unlike an induction loop system. Larger emitters are used in court rooms and theatres. As the size of the room and the amount of people wishing to hear increases, additional emitters and receivers will be required.
The system works in the same way as a remote control on a video or television, i.e. an emitter (the remote handset) sends out an invisible beam of infrared light which individual receivers (the TV), convert into sound via built-in headphones.