Written and maintained by CASRAI Editorial Board
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This page describes products and general use; it is not medical advice.
An assistive listening device (ALD) is equipment that makes the sounds a person wants to hear louder and clearer, especially where there is background noise. The NIDCD, part of the US National Institutes of Health, says ALDs can be used with or without hearing aids or cochlear implants. Who uses them: people with hearing loss, and the schools, theaters, courtrooms, places of worship, airports and clinics that install systems for them.
What is an assistive listening device?
An ALD is a device or system that improves sound transmission for a listener with hearing loss. NIDCD describes some as designed for large facilities such as classrooms, theaters, places of worship and airports, and others as intended for personal use in small settings and one-on-one conversations.
The 2010 ADA Standards define an assistive listening system as an amplification system using transmitters, receivers and coupling devices, which bypasses the acoustical space by induction loop, radio frequency, infrared or direct-wired equipment. That definition is a useful way to read any ALD: a transmitter picks up the sound, a receiver is worn or held by the listener, and a coupling device (for example a telecoil, headset or earbuds) delivers it.
How assistive listening devices work
ALDs move sound from the source to the listener without relying on the whole room’s acoustics. Because the sound is sent directly, much of the competing background noise is avoided. The transmission medium is what separates the main system types: electromagnetic energy (hearing loop), radio signals (FM), or infrared light.
Types of assistive listening devices
| Type | How it transmits sound | Key difference or limit (NIDCD) |
|---|---|---|
| Hearing loop (induction loop) | Electromagnetic energy through a wire loop; picked up by a telecoil or a loop receiver with headset | Listener must be within or near the loop; portable loop receivers exist for people without a telecoil |
| FM system | Radio signals; speaker wears a microphone and transmitter, listener wears a receiver tuned to a channel | Transmits up to 300 feet; radio passes through walls, so nearby rooms may need different channels |
| Infrared system | Infrared light beamed from a transmitter to a worn receiver | Cannot pass through walls; cannot be used where there are too many competing light sources, such as outdoors or in strongly lit rooms |
| Personal amplifier | Boosts sound and reduces background noise; about the size of a cell phone | Useful where the other systems are unavailable, or for TV, outdoors or travel in a car; some have directional microphones |
For deeper coverage of individual types, see the CASRAI guides on the induction loop, the FM system, the hearing aid telecoil and the voice amplifier for teachers. Clinics stocking this equipment can also use the audiology clinic supply checklist.
Alerting devices versus listening devices
NIDCD treats alerting devices as a separate group. They connect to a doorbell, telephone or alarm and use sound, light, vibration, or a combination, to let a person know an event is occurring. They do not amplify speech, so they are not the same as the listening systems above.
How to choose
NIDCD describes these situations.
- Large rooms such as classrooms, theaters and places of worship: loop, FM and infrared systems are the facility-scale options.
- Rooms where signals must stay inside the room (NIDCD cites courtrooms handling confidential information): infrared, because the signal does not pass through walls.
- Outdoors or strongly lit rooms: infrared is not suitable.
- Listener without a telecoil: a loop receiver with headset is available, though NIDCD notes it lacks the customized sound of a telecoil matched to the hearing loss pattern.
- TV, outdoors or a car: personal amplifiers.
Regulation: not every ALD is the same kind of product
In the United States, FDA regulates the group hearing aid or group auditory trainer at 21 CFR 874.3320, a hearing aid intended for communicating simultaneously with one or more listeners with hearing impairment. That regulation describes this FM-type category; it is not a rule covering every ALD. Facility installations are addressed separately by the ADA Standards, which an installer should read directly.
Safe use and handling basics
- Match the receiver to the transmission type: a telecoil picks up a loop signal, and a neckloop or silhouette inductor converts FM or infrared signals for a telecoil (per NIDCD).
- With FM, check channels when neighboring rooms use systems at the same time.
- Follow the manufacturer’s instructions for use for fitting, battery care and cleaning.
- Questions about which device suits an individual belong with an audiologist.
Common mistakes
- Choosing infrared for an outdoor or sunlit space.
- Expecting FM signals to stay in one room.
- Assuming every hearing aid has a telecoil; NIDCD describes the telecoil as built into many hearing aids and cochlear implants, not necessarily all.
- Treating alerting devices as speech amplifiers.
Frequently asked questions
What does an assistive listening device do?
It amplifies the sounds a listener wants to hear and reduces the effect of background noise, with or without hearing aids or cochlear implants (NIDCD).
Do I need a hearing aid to use one?
No. NIDCD states ALDs can be used with or without hearing aids or cochlear implants; a headset or earbuds can act as the receiver.
What are the main types?
Hearing loop, FM and infrared systems for facilities, personal amplifiers for individual use, and separate alerting devices.
Sources
- NIDCD (NIH), Assistive Devices for People with Hearing, Voice, Speech, or Language Disorders, checked 2026-10-31.
- US Access Board, 2010 ADA Standards for Accessible Design (also at ada.gov), definitions, checked 2026-10-31.
- eCFR / LII, 21 CFR 874.3320 Group hearing aid or group auditory trainer, checked 2026-10-31.
