What is Assistive Listening Devices
An assistive listening device (ALD) is type of device that can help you function better in your day-to-day communication situations. An ALD can be used with or without hearing aids to overcome the negative effects of distance, background noise, or poor room acoustics. So even though you have a hearing aid, ALDs can offer greater ease of hearing (and therefore reduced stress and fatigue) in many day-to-day communication situations.
Hearing aids + ALDs = Better listening and better communication!
Types of ALDs
- Personal frequency modulation (FM) systems
- Infrared systems
- Induction Loop Systems
Personal frequency modulation (FM) systems:FM System Improves the Signal-To-Noise Ratio and thus the user’s ability to understand Speech in Noise. Three major Facts as background noise, Reverberation and distance are influence the SNR & Quality of Speech Signal. By developing the Signal of interest via FM (Radio Wave) The strength and quality of sound remain constant across the distance from the speak to the hearing impaired individual. FM System consists of a transmitter with a microphone and a speaker, which pick up the signal via radio wave directly from the transmitter.
Infrared systems are often used in the home with TV sets, but, like the FM system, they can also be used in large settings like theaters.
Sound is transmitted using infrared light waves. The TV is set at a volume comfortable for family members. The infrared system transmitter transmits the TV signal to your receiver, which you can adjust to your desired volume. Thus, TV watching as a family becomes pleasurable for all. While it is not too loud for family members with normal hearing, the volume is just right for you because it is adjusted by you through your individual receiver.
Induction Loop Systems are most common in large group areas. They can also be purchased for individual use.An induction loop wire is permanently installed (perhaps under a carpet) and connects to a microphone used by a speaker. The person talking into the microphone creates a current in the wire which makes an electromagnetic field in the room. When you switch your hearing aid to the “T” (telecoil/telephone) setting, your hearing aid telecoil picks up the electromagnetic signal, and you can adjust its volume through your hearing aid.