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Classroom Assistive Listening Devices

Anyone who wears a traditional hearing aid knows of the disadvantages – everything is amplified, including unwanted background sounds. Even the best digital hearing aids cannot completely eliminate the amplification of background noise. For a child with a hearing impairment in a classroom this can prove to be a major obstacle in their education.

Classrooms typically have very bad acoustics. Sounds from echoes, scraping chairs and background chatter can make it difficult for a hearing impaired child to understand the teacher. Even if the student is seated near the front of the classroom and the teacher is paying particular attention to their needs by directly facing the child and speaking clearly, the child can still miss a lot.

Fortunately, there are a number of Assistive Learning Device (ALD) systems available to help hearing impaired students. The four major ALD systems for use in the classroom are the FM system, the Sound Field system, the Loop system and CART. Each one has its merits.



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If it is determined that usage of the assistive listening device is necessary for the hearing impaired student to receive a Free Appropriate Public Education (FAPE), then the child’s school district is obligated to provide the equipment at no charge to the family under either a 504 or Individualized Education Plan (IEP) if the child is school aged, or an Individualized Family Services Plan (IFSP) if the child is 0-3.


FM systems use a wireless transmitter to broadcast a signal throughout a given area. The size of the broadcast area is determined by the power of the transmitter, with an auditorium typically being the maximum practical size.

The teacher wears a transmitter and the student wears a receiver. Nowadays the receiver is very small and may be integrated into the child’s hearing device. The signal from the receiver is fed into an earphone or the student’s own hearing aid.

The teacher speaks into a small microphone. The microphone is often worn on the lapel – about 5 to 7 inches from the teacher’s mouth. The microphone is very sensitive and can pick up sounds like fabric or jewellery rubbing against it.

Using the FM system, the student can hear the teacher clearly anywhere in the broadcast area. If the teacher has his back to the class, his voice will still be clearly heard by the students with the receiving device.

One advantage of this system is its portability. The transmitter is small and can be used in any room. No permanent installation is required, and the student has his own receiving device.

The FM system can be used to amplify the human voice, a movie soundtrack or other audio source, making it ideal for classroom use.


Sound field systems are similar to FM systems in that they both use FM radio waves to transmit the desired sound. But whereas FM systems only benefit those students with a receiver, sound field systems are designed to overcome poor classroom acoustics, thereby benefiting all the students.

The teacher wears a small microphone and his or her voice is broadcast to loudspeakers placed strategically throughout the classroom. The sound of the teachers voice is amplified enough to compensate for background noise. Students in the back of the room can hear as clearly as those in the front.

Sound field systems are useful for students with mild to moderate hearing loss. They also provide benefits to the teacher. She can maintain voice contact with every student in the classroom without raising her voice. All students in the classroom are better able to concentrate on what the teacher is saying.

These systems are less portable than the FM systems due to the installation of the loudspeakers. Because they benefit other than just hearing impaired students, though, their permanent installation can be easily justified.


Loop systems have been used for many years, being more popular in Europe than in America. Based on telephone technology, it is a time proven system for aiding those with hearing loss.

Loop systems use a cable that circles the listening area. The loop can be any size, and can be placed anywhere. It could be around a classroom, an auditorium, a table (for conference work) or even around a car.

The teacher speaks into a microphone and the signal is amplified and fed through the loop. Students receive the signal through specially equipped hearing aids that receive electromagnetic signals. These hearing aids are very common, and have a built-in “T switch” (telecoil switch).

Approximately 30 to 40 percent of hearing aids already have integrated telecoils. For people with such a hearing aid, this system is very easy to use. There is no need for a separate receiver, as is the case with FM systems.

Loop systems are relatively easy to install and therefore economical. Several small looped systems could easily be installed in various school areas – the library check out desk, the office, anywhere the hearing impaired student needs to communicate effectively.


For students with severe hearing loss, the CART (Communication Access Realtime Translation) system can be of great benefit. Originally used for court transcription, CART has found new applications in the classroom.

A specially trained CART operator uses a transcription machine to record all spoken text. The text is displayed either on a computer monitor or projected on a screen.

One benefit of this system is that all speech is recorded, not just that of the teacher. This allows the hearing impaired student to keep up with comments from other students, and participate more fully in the classroom.

Another benefit is that there is a written record of everything said in the classroom. The teacher can use these transcripts to review his classroom material and student remarks. If the teacher decides to make the transcripts available to students, they can use them as a study aid.

The CART system is usually only seen in university or college level institutions. The cost is greater than other systems because of the need to pay an operator. Students who have had access to CART, however, often prefer it over other Assistive Learning Devices. They can understand better what is going on in the classroom and play a more active role.

In California a court recently determined that a CART system was necessary for a deaf high school student who was a cochlear implant user in order to receive FAPE. http://www.documents.dgs.ca.gov/oah/seho_decisions/2006110090.pdf


Whatever Assistive Listening Device is recommended by a hearing impaired child’s audiologist is only part of the solution. State of the art hearing aids and skilled, professional programming and fitting, like that provided by the audiologists at the Hearing Device Center of the California Ear Institute, and acoustical modifications may also necessary to creating the optimal listening environment for any hearing impaired individual. Click here to make an appointment to improve your hearing today !


Here are some manufacturers of ALD’s.

Phonic Ear
Listen Technologies Corporation
NADY Systems Incorporated
Sennheiser Electronic Corporation
Williams Sound

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