Fm systems or fm amplification devices are often used in classrooms to help students with a hearing loss gain access to information. There are several types of systems. Generally students use an fm system that attaches to their personal hearing aids. Two boots or audio shoes are attached to their hearing aids with a receiver. This piece receives the signal from the microphone and sends it through the hearing aid. Only the student hears through this system. The teacher wears a microphone clipped to their shirt or hung around their neck. Some have boom mikes similar to those seen at concerts that are worn at the mouth level. The teacher’s voice is transmitted directly to the student’s hearing aids.
Another type of fm system is a sound field system. These provide amplification for the whole classroom or have a speaker that sits on a student’s desk. Other people can hear through this system. These are generally used for students with mild hearing loss or with students that have attention difficulties or other disabilities. Sound field systems also are used in general education classrooms to improve acoustics. Teachers find them extremely beneficial and find that their voices are not strained, they have less hoarse voices, and they are able to project better.
Why do students need this assistive device? Classrooms tend to be noisy. The background noise in a classroom competes with the preferred auditory information; the teacher’s voice or the other student’s voices. Background noise comes from the environment as well as the people in the room. Step into an empty classroom and listen. You will probably hear humming noises from the ventilation system, lights and computers. You may hear street noise or sounds from nature. You may hear hallway noise or the teacher in an adjacent or nearby classroom. All of these sounds are competing with the intended signal.
Now add the students and other adults in the room. The background sounds may be whispering, chairs moving, shifting in a chair, papers rattling, pencils tapping, coughing, etc. Even the best classroom management skills do not eliminate the extra sounds people make.
FM systems reduce the background noise and boost the speaker’s voice slightly to make it stronger and more easily heard. This increases the signal to noise ratio. Ideally the signal, the teacher’s voice, should be at least 15 decibels louder than the noise (background sounds) to be heard easily. This often does not happen in classrooms for a variety of reasons including those described above and the design of the school buildings. Hearing aids amplify all sounds including the background noises. The fm system helps hearing aid users by reducing the background noise which makes the signal more audible. Students with cochlear implants also benefit from this technology. This alone helps students pay attention better.
The other advantage of an fm system is that it allows mobility. Ideal communication distance for students with hearing aids or cochlear implants is four to six feet. Teachers would have to stand directly in front of these students and at their eye/ear level to have optimal distance to be heard. Think about how much more difficult hearing becomes when you are further apart from the speaker. Most people with typical hearing will move closer to hear better. Obviously a teacher cannot stand in one place all the time and it would not be natural to maintain the appropriate speaking distance. With the fm, the teacher’s voice maintains approximately the same strength and volume at any distance. If the teacher walks to the opposite end of the room and speaks, the student will hear their voice at the same level as if they were speaking 4 feet away. For students that use speech reading and visual cues, this helps when a teacher turns their head. At least they can still hear what is being said and would have a better chance to fix errors or make sense of the message.
How do you use an fm system? Fm technologies have come a long way over the years. Most systems are very easy to use. Teachers wear a microphone around their necks or attached to their shirt and clipped on their belt. They turn it on and speak normally. At the end of the day, the microphone needs to be charged. Plug it in as you would a cell phone and you are ready for the next day. The student attaches the receiver to their personal hearing aid or implant. It runs off the batteries in their device. The fm usually needs more battery power than the hearing aid or implant alone so they will have to change the battery more often. Depending on the age of the student, the receivers can remain on all day or can be taken off for recess and lunch so they are not lost.
Teachers wear the microphone about 6 inches from their chin.
Turn off the mike when not speaking to the group or directly to the student using the fm. It will transmit from a distance. If you have it on and go to the bathroom or out to the hall, they will hear you. Many private conversations or embarrassing situations can be avoided by turning off the mike!
Students can also hear static when out of range. Students with hearing aids are generally able to switch the fm off at their ear level if they hear noise. Some cochlear implant fm systems and some younger students may not be able to change the settings on their own.
Plug in the mike to charge it at the end of the day. Turn it off before plugging it in.
Use it consistently. Report problems to the teacher of the deaf or to the audiologist.
Fm systems are generally set up by audiologists. They have access to the latest and most appropriate equipment. They are also able to set them to their hearing aids.
For more information and links, see the links section of this blog.
Posted in Classroom Resources | Edit | No Comments »