Assistive Listening Devices
(ALDs)
An Assistive Listening Device is any device other than hearing aids that are designed to improve a person's ability to communicate and to function more independently despite a hearing loss. There are many types of devices available which are in two basic categories.
1) ALARM DEVICES These devices are sensory devices, which warn, signal and alert. They function by providing one or more tactile, visual and/or auditory signals. Examples include:
- Wake-up alarms
- Smoke detectors
- Door bell detectors
- Telephone ring detectors
- Other sounds detectors
These devices work by providing a vibration, flashing light or louder signal in a frequency range that can be heard which will alert the person to the particular sound.
2) LISTENING DEVICES Listening devices are designed to bring the listener closer to the source of the desired sound. They reduce undesirable background noise and provide greater clarity for speech. There are four main categories: Loop, FM, Infrared and Hardwired.
- Loop system A Loop System is a loop of wire around a room. This system uses the hearing aid's telephone switch. The loop is connected to an amplifier that receives signals from the sound source. This system can be used for groups, small or large. There are large systems in some churches, theatres and meeting rooms. Small portable systems are now available for home use.
- FM system FM system is a radio system consisting of a small transmitter and microphone. The microphone is placed near the sound source and the signal is sent to the receiver which the person wears.
- Infrared system Infrared systems consist of a transmitter and receiver. A microphone is placed near the sound source and the signal is transmitted to the person by lightwaves.
- Hardwire systems This system is similar to the others except that the person is directly "wired" to the microphone or transmitter. It is designed for small areas at home.
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