FM SYSTEM
ASSISTIVE LISTENING DEVICES
What is an FM System?
An FM system improves the transmission of sound, thereby making speech more accessible to the person
using it. The speaker wears a lapel or neck loop microphone and transmitter about the size of a PDA.
The other person has a receiver about the size of a PDA and wears a headset or plugs the wire from the
receiver into a hearing aid. An FM system is similar to an FM radio station that "broadcasts”
the speaker’s voice to a listener's FM receiver.
How FM Systems can Help
FM systems improve the "signal-to-noise" ratio, so it seems as if the speaker is standing
right next to the listener’s ear. The clarity of the signal and the amount of information received
varies according to the level of ability to process information or, if the listener has a hearing
impairment, the degree of loss. The listener may need to have a clear view of the speaker's mouth,
if he/she reads lips. The FM system also filters out background noise, which enhances the strength
and clarity of the signal received by the listener. The result is improvement in sound accessibility
that can be quite pronounced. Hearing aids do not filter out background noise; they amplify all
sound equally, which is fatiguing for the listener.
Recommendations on How to Use the FM System
- The student is responsible for bringing the equipment to class and managing it.
- The speaker should attach the lapel or neck loop microphone 3-5” from the mouth.
- Perform a listening check each time it is used.
- Speak clearly in a normal tone of voice; face the person with the receiver and do not
over-enunciate.
- During class discussions, the professor should allow only one speaker at a time and pass the
transmitting microphone to the speaker. If that is not feasible, the professor should repeat the
speaker’s comments and/or questions before responding to the class.
- For small groups, such as seminar classes, the student can borrow a conference microphone from
DSS that is placed in the middle of the table.