Author: Dolly Bhargava, M. Spec. Ed. 


What is an FM system?

A frequency modulation (FM) system can be used by teachers to transmit their voice directly to the student and can be used indoors and outdoors. It consists of:

  • Microphone
  • Transmitter and
  • Receiver

How Does an FM System Work?

The sound (e.g. teacher’s voice) is picked up by a microphone which is connected through a line input to the transmitter.  The sound signals are then picked up by the receiver that is worn by the student with hearing impairment. There are several options for getting the sound from the receiver to the ear depending on the student’s degree of hearing loss and personal preference (Downie, 2000).  If the student wears hearing aids, normally there is a lead that physically connects the FM receiver to the hearing aid (called direct audio input). 

An FM system can also be used with headphones that directly transmit the teacher’s voice to the student, resulting in less distraction by other noise in the room and better understanding of what the teacher is saying.

An FM system can also be used in a classroom to transmit other audio signals to the student, such as television and radio.  This can be done using an audio lead that takes the audio signal from the sound source and connects it to the auxiliary input on the FM transmitter.

Systems that use an FM signal can transmit through walls, so it is important to remember to turn off the transmitter when you leave the room or wish to discuss something in private or confidentially, as otherwise the student may be able to overhear your conversation.

Depending on the FM systems being used by students, it is also possible to transmit the signal from PA systems in halls and stadiums on the school grounds directly to the student’s receiver.  This is a convenient means of providing access to students with hearing impairment to schools that use a PA system. This process uses a product called a large area transmitter.


Benefits of FM Systems

  • They can be used with students with a wide variety of hearing impairments.
  • The student is able to receive high-quality sound over considerable distance (Downie, 2000).
  • The FM system enables the student to hear the person speaking into the microphone clearly and without most of the background noise.
  • The student can hear the speaker clearly even when the speaker is not close by or is moving around the room.
  • The FM systems are portable and can be easily moved from one class to another and used in situations where other classroom amplification systems are not practical (e.g. on the playground or during field trips)  (Lewis, 1998).

Tips for Teachers Using FM systems

  • It is important to wear the transmitter.
  • Enquire whether or not the student has been issued an FM system and encourage its use.
  • The speaker needs to be aware of the volume of his/her voice as it is being directly broadcast to the student.
  • The speaker must take care to eliminate interfering noise.  For example, ensure that the microphone does not rub on clothing (Downie, 2000), the speaker’s hair does not rustle against the microphone and the speaker does not clear his/her throat or eat whilst talking.
  • The speaker wearing the transmitter needs to remember to turn it off when not interacting with the student wearing the FM receiver. 
  • During group discussions, try to pass the microphone to each child who speaks (Trautwein, 2005) so that the student wearing the FM receiver can hear all contributions.
  • If two transmitters are being used in the same classroom, e.g. in a team teaching situation, ensure that the transmitting frequency channels are as distinct as possible. Remind the student to change channels as they move from group to group (Trautwein, 2005).
  • For multi-media lessons on TV, CD or DVD, place the FM transmitter microphone near the sound source, or preferably connect the TV directly to the FM transmitter via the auxiliary input jack (Trautwein, 2005).