Assistive Listening Devices for Hearing Impaired People
Assistive Listening Devices (ALD) are any technology developed to enhance the abilities of a person who is hard of hearing, to better hear and understand public presentations. These systems can be used with a television set, in small gatherings, in class or meeting rooms, and in venues like churches, auditoriums and theatres.
What do they do?
ALD's amplify or enhance sound. Because these systems and devices frequently tap directly into the source of the sound by using a microphone clipped to the speaker or suspended above a stage or a wireless microphone, they help hearing a desired sound by cutting down ambient noise, amplifying sound or by eliminating the distance between the speaker and the listener. The primary job of the ALD is to make the source sound louder and/or clearer and to give volume control to the individual.
Who needs to use Assistive Listening Devices?
An estimated 3.25 million Australian adults, or 16.6% of the population, are deaf or hard of hearing. Deafness has been defined as the second biggest health issue facing Australia today. Of this percentage many individuals have some residual hearing that enables them to benefit from the use of assistive listening systems or Hearing Aids.
How do Assistive Listening Devices Work?
ALD’s consist of a transmitter and a receiver, in some cases the hearing devices of the user has a built in receiver (“T” switch or telecoil).
The induction loop system broadcasts via electromagnetic (radio) waves within an area encompassed by a big wired area (the loop). To get amplification the userl must be seated within the looped area and use their own telecoil switch in their hearing aids or a special receiver unit .
The FM and Bluetooth system operates just like a small radio station with pre-set frequencies; these devices can be plugged directly in to the hearing device or work together with the telecoil switch of the hearing aids.
The infrared system is known as a "line of sight" system since the receiver must be in line of sight of the trasmitter because infrared waves will not go through a solid object.