by Amber Hodgson, M.A., CCC-SLP
A Frequency Modulation System or FM System is a type of assistive listening device. Assistive listening
devices are pieces of equipment that help individuals maximize their ability to hear, especially in difficult, or
noisy, situations. For children, the classroom environment is one place that can be particularly noisy. Not only
do classrooms often have poor acoustics (sound quality in a space), but they also have lots of background
noise, like fans, air conditioning, moving desks/chairs/feet, talking from other students, and outside sounds,
like traffic. All of these sounds compete with the teacher’s voice. These noises can make listening and
learning extremely challenging, especially if a student has a hearing impairment or an existing disorder, such
as auditory processing, attention deficit hyperactivity disorder, or autism.
How Does an FM System Work?
An FM system helps make the sound of the teacher’s voice louder than the competing background
noises. To do this, the teacher wears a microphone, which attaches to a transmitter. The microphone picks
up the teacher’s voice then transmits it to the receiver. The receiver brings the sounds to the student’s ears.
An FM system can also work with hearing aids.
There are two types of FM Systems—Personal and Sound Field. Personal FM systems include behind-the-
ear (BTE), where a receiver is built into a hearing aid, and body-worn where a receiver is attached to
walkman-style headphones. A sound field FM system amplifies (makes louder) the teacher’s voice through
loudspeakers. With a sound field FM system, all of the students in the room receive the teacher’s amplified
voice over the present background noise.
How Does an FM System Help?
FM systems help to maximize a student’s hearing and learning abilities for success in the classroom.
FM systems can help by:
- Reducing distractions, such as background noise.
- Increasing understanding of speech, especially if the teacher’s back is turned.
- Improving attention to a task.
- Decreasing listening effort, therefore helping to reduce fatigue.
An educational audiologist can select, evaluate, and monitor an FM system
for a student(s) to use at school. The educational audiologist can also provide
instruction to the teacher and other school staff members on how to use the device.