Frequency Modulation (FM) Systems

Hearing aids alone do not make listening easier in all situations. Background noise, distance, reverberation, and echo can all interfere with listening.

Babies and young children listen in difficult situations every day – listening in the car, at day care, and playing outside or at the park. FM systems are used to help overcome the challenges of listening in noisy places.

Parts of an FM System

FM systems work like small radio stations. There is a small radio transmitter attached to a microphone and a small radio receiver. A parent or teacher wears the FM transmitter and microphone while the child wears the FM receiver. Listening to the FM signal is like listening to someone talking from only 3 or 6 inches away; even if that person is across the room.

Roger Inspiro transmitter pen and receiver 

Microphone Options

  • Lapel microphone: worn at chest level and placed about 6 inches away from the mouth to pick up the best signal.
  • Boom microphone: a mouth-level microphone placed about 3 inches away from the mouth.
  • Conference microphone: a microphone can be placed on a table to allow the person using the FM to hear more than one voice around the table.
  • Directional microphone: Some microphones can be directional, which helps the FM microphone to focus on one talker in a background of high noise. Some directional microphones can be held by the listener who points the microphone towards the person they want to hear.

Transmitters

The FM transmitter receives the signal from the microphone and then sends the low-power radio signal to the FM receiver. The receiver needs to be within about 50 feet of the transmitter to pick up the signal. The radio channels used by FM transmitters have been set aside for educational use in the United States.

Receivers

The FM receiver gets the signal sent by the transmitter and sends it to a personal hearing aid, cochlear implant processor or other device.

  • FM receivers are either worn on the body or worn at ear level. 
  • Some FM receivers work without a hearing aid and others must be connected to a person's hearing aid.
  • Ear-level receivers are the most convenient, smallest in size and are often recommended when using FM systems at home.

Where Should FM Systems Be Used?

In the past, FM systems were only used in schools to help students listen in noisy and reverberant classrooms. Now, many pediatric audiologists recommend that FM systems are also used at home.

Using FM Systems to Communicate at Home

Imagine a parent and child at home in the kitchen – while the parent is working at the stove or sink their back is turned to the child. However, if the child uses an FM system he or she can easily hear what the parent is saying, no matter the direction they are facing.

Additionally, FM systems keep the listening distance close no matter what the child is doing. Many families say that using an FM system at home gives them more opportunities to interact with their child in daily activities. Children report that using the FM system gives them a feeling of security when they are at a distance from their parents, such as in the grocery store or on a family outing. This may help children develop self-esteem and independence.

Some activities where FM systems work well are traveling in the car or van, visiting the zoo, playing in the park and shopping at the grocery store.

  • When babies start to crawl and walk, the listening distance between the child and his or her parent can change quickly.
  • Children who are busy playing or exploring often do not look at a person that is speaking to them.

Using FM Systems in the Car

The car is a difficult listening situation – lots of background noise, the child cannot see the parent's face and there is added distance between the front and back seats. A hearing aid alone cannot overcome all these difficulties.

For families that spend a lot of time in the car, using an FM system provides a better communication connection between the parent and child.

Overhearing

Research shows that overhearing conversations helps children learn new words and improves their understanding of how to use language.

  • Children with hearing loss may miss opportunities to overhear if people are talking more than 1 meter away or if it is noisy.
  • Using the FM with a hearing aid can give a child more opportunities to overhear some conversations, which may lead to vocabulary growth.

Operating FM Systems

Parents need to decide when and how the FM system should be used. FM operation is controlled by a switch on the FM receiver or by remote control. There are different settings from which to choose when an ear-level FM receiver is connected to the child's hearing aid:

  • Hearing aid only, with no signal from the FM microphone
  • FM only, with no signal from the hearing aid
  • Hearing aid and FM together

The FM microphone should be turned on when the parent is talking to the child in a noisy situation. It also should be turned on when the parent is going to be at a distance from the child, but wants the child to hear her voice at a stable level. The hearing aid microphone usually stays on so that the child can hear other sounds and voices around them. When the hearing aid is on, the child also can hear his own voice.

Cost of an FM System

Buying an FM system for home use is an additional expense beyond personal hearing aids. An FM package, including the transmitter/microphone and ear-level receivers may cost around $2,500. If extra warranties or special microphones are needed, the cost may be higher. Parents often look for financial help to buy an FM system. Insurance policies often do not cover FM systems. Families should work with their audiologist to find funding.

For further information on FM products: