Assistive listening systems (ALS)
Assistive listening systems (ALS) or assistive listening devices (ALD) are amplifiers that bring sound to the ear and separate sounds such as speech from background noise. ALDs improve speech to noise ratio, boosting the level of understanding for people who have problems distinguishing speech in noise to the same level as people with normal hearing ability.
Audiologists may suggest they use a microphone, transmission technology and a device for receiving the signal and bringing sound to the ear. Types of ALDs include telephone, FM, infrared and inductive loop. With the exception of telephone amplifiers, ALDs broadcast sound wirelessly.
- Telephone amplifiers increase the volume of your telephone and attach directly to the telephone headset. They include built-in volume control.
- FM ALDs use radio broadcast technology and are often used in educational settings for improved mobility when used with portable, body-worn transmitters.
- Infrared ALDs use light-based technology and guarantee privacy because infrared does not travel through walls. They are typically used for entertainment such as television listening because they are frequently installed in places of entertainment.
- Inductive loop ALDs use electromagnetic fields to deliver sound and do not require a body-worn receiver. They can also be used by non-hearing aid users through headphones and inductive loop receivers.