FM stands for frequency modulated. It is probably the best known system. It is made up of a transmitter, which can be thought of as a small radio station, and a portable receiver, comparable to an FM radio. The system transmits sound using FM radio signals.
They are very easy to set up, operate, and use. And they may be the better system for students with a more severe hearing loss, because they have a greater acoustic output (they can be turned up louder) than infrared.
You may have used an FM system without realizing it. Crib monitors are an common example of FM systems in use today. The transmitter is in the room with the baby, and the receiver is placed wherever the caregiver is. If the baby makes noise in one room, it can be heard over the monitor in another.
