Hearing Assistance Devices

Over 15 million people in this country experience some degree of hearing loss. And, a person with hearing loss must strain to hear. Background noises such as people talking, coughing and even pages turning can make it extremely difficult for students to hear the teacher. Please take a moment to look at the tools available to help individuals that suffer with a loss of hearing.

There are basically three types of assistive hearing systems: inductive loop systems, FM wireless systems and infrared wireless systems. The following is a straightforward description of each of these systems and their inherent advantages and disadvantages.

Figure 1

Inductive Loop Systems:

The equipment of this system is a transmitter and multiple receivers. The transmitter is connected to a wire which loops the entire seating area. This loop enables everyone with a receiver or a hearing aide with a T-coil to hear the sound system. Sounds like a good theory. But, the reality is it's expensive and difficult to install. The inductive system is also prone to interference. So, keep reading for more options to help your students that have hearing difficulties.

Figure 2

FM Wireless System:

This format is the most common type of assistive hearing system, often used in churches and other small public facilities. Typically, this system is monaural (one ear piece). It is comprised of an FM radio-frequency transmitter and several pocket-sized receivers with a detachable ear piece and cable. The receiver is battery-powered and has an integral volume control. The transmitter can be rack-mounted or located with the other sound system equipment. An auxiliary output signal from the sound system is connected to the transmitter's input.

Although this type of system is usually the most cost-effective, it has one major disadvantage when compared to an infrared wireless system. The signal transmitted by FM wireless systems will permeate most walls and some ceilings or floors. So what? Well, here's the problem: Let's say you have simultaneous events occurring in the auditorium and the gymnasium. A person using an FM receiver in the gym will hear interference from the auditorium assistive hearing system.

You can avoid this problem by using a system in each room that is on a different frequency than any other system in the building. However, there are two problems with this. First of all, there will be more rooms than there are available, compatible frequencies.

More importantly, keeping the receivers for each system frequency separate from other receivers is an inventory nightmare.

Figure 3

Infrared Wireless System:

Infrared wireless systems are the best option for several reasons. First of all, infrared transmissions will not permeate walls, ceilings or floors. This means each room has total privacy from any other room. Since infrared systems are not hampered by multiple frequency problems, a person wearing an infrared receiver in one room can move to another room and use the same receiver unit without switching frequencies or units entirely. You may be familiar with some museum or tour facilities that use infrared systems. As you move from room to room, you automatically hear the presentation specific to the room you are in.

Infrared systems can also be set-up to provide stereo sound. This is especially beneficial in theater, auditorium facilities, lecture halls or presentation rooms where high quality audio is being produced as a part of a video tape or laser disc.

Infrared headsets have the receiver unit built into the headset. No wire or connector failures can occur.

For a small to medium size room, infrared systems will be similar in cost to FM wireless systems. As the size of the room increases, additional emitters (similar to transmitters in FM systems) may be required.

All things considered, infrared systems are usually the best choice for many multi-room public facilities.

One Additional Note:

An assistive hearing system can provide an additional benefit that will significantly increase local community support and attendance. Using one of the receiver units with a simple adaptor cable, you can provide wireless sound input for individual video camcorders. Read that again. Parents, grandparents, local cable access tv, etc. can get their own wireless audio feed from the sound system!

by Travis Ludwig © 1996 Internet Sound Institute (www.soundinstitute.com). This article is for personal use only. Any commercial reproduction is not permitted without permission. To obtain permission, contact ISI at hopi@soundinstitute.com

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