Infrared systems are widely used in theaters, auditoriums, courtrooms, meeting rooms, etc. The transmitter uses invisible light waves to send sound to individuals wearing a wireless receiver. A major advantage of the infrared system is that infrared receivers are compatible with most vendor transmitters. For example, a Sennheiser infrared system installed in an auditorium may transmit to an individual's personal Audex receiver without difficulty. Infrared systems may not be effective in rooms where there is a lot of sunlight.
Most infrared systems have several receiver options available.
Body worn receivers can also be used with various headset options. Individuals who do not have a telecoil built into their hearing aid, who prefer not to use the telecoil on their hearing aids, or do not wear a hearing aid, may want use the walkman-style headsets or earbuds. A silhouette inductor works like the inductor neckloop except it is worn behind the hearing aid. Another option that is becoming more popular when using an infrared system is a walkman-style headset which has the receiver built into the headset. Direct audio input is used by very few people since it requires a special hook-up with the hearing aid.