Other devices, such as personal computers, were originally developed for general purposes, but nevertheless afford important secondary benefits to people with hearing loss. Such systems can also help minimize background noise and can help compensate for poor acoustics. Loops transmit an electromagnetic field, infrared systems emit light waves, and FM systems send radio waves. Each works well, operates without wires, and can be used with or without hearing aids. An array of receiver attachments is available to meet varying individual needs and listening preferences.
Infrared systems offer the advantage of privacy.
Such systems might be a good choice for courtroom situations because the light waves they transmit don t pass through walls. FM systems are portable, making them a popular choice for classroom situations, since both the teacher and student can use battery-operated components, and the student can move around without interfering with reception. All three systems are susceptible to interference. Loop systems are occasionally affected by electromagnetic fields, but some sources, such as computer monitors, can be turned off at times. Sunlight or certain fluorescent lights can affect infrared systems, but a more powerful emitter and a newer model receiver may help compensate for that.