However, some wall-coverings absorb infrared light rather than reflecting it, so that receivers only work when they are pointed at the radiators. This can be a problem, as the listeners may lose sound if they turn away slightly from the direction of the radiator. Infrared systems are not usually prone to interference unless the receivers are in direct sunlight. The radiators do not radiate outside the room they are used in, so several systems can be used simultaneously in adjacent rooms and they are suitable for confidential meetings. Infrared systems are fairly easy to install and provide high quality sound.
Stereo versions are available.
Whichever system is installed, the quality of the signal it produces can only be as good as the signal it receives. Neither loops nor infrared improve signal quality - they simply reproduce what is fed into them. It is easy to get a clear signal when this comes from a person speaking direct into a microphone. The further the sound has to travel to reach the microphone, however, the more it is corrupted by room acoustics and background noise. The microphone must therefore be placed where it can receive sound well.