U.S. DEPARTMENT OF HEALTH & HUMAN SERVICES ∙ NATIONAL INSTITUTES OF HEALTH ∙ NATIONAL INSTITUTE ON DEAFNESS AND OTHER COMMUNICATION DISORDERS

NIDCD Fact Sheet

Assistive Devices for People with Hearing, 

Voice, Speech, or Language Disorders

hearingbalance

This logo informs people that a public area is looped. 

Source: HearingLoop.org 

What are assistive devices?

The terms assistive device or assistive technology can 

refer to any device that helps a person with hearing 

loss or a voice, speech, or language disorder to 

communicate. These terms often refer to devices that 

help a person to hear and understand what is being said 

more clearly or to express thoughts more easily. With 

the development of digital and wireless technologies, 

more and more devices are becoming available to help 

people with hearing, voice, speech, and language 

disorders communicate more meaningfully and 

participate more fully in their daily lives.

What types of assistive devices 

are available?

Health professionals use a variety of names to describe 

assistive devices:

• Assistive listening devices (ALDs) help amplify

the sounds you want to hear, especially where

there’s a lot of background noise. ALDs can be used

with a hearing aid or cochlear implant to help a

wearer hear certain sounds better.

• Augmentative and alternative communication

(AAC) devices help people with communication

disorders to express themselves. These devices can

range from a simple picture board to a computer

program that synthesizes speech from text.

• Alerting devices connect to a doorbell, telephone,

or alarm that emits a loud sound or blinking light to

let someone with hearing loss know that an event is

taking place.

What types of assistive listening 

devices are available?

Several types of ALDs are available to improve 

sound transmission for people with hearing loss. 

Some are designed for large facilities such as 

classrooms, theaters, places of worship, and 

airports. Other types are intended for personal use 

in small settings and for one-on-one conversations. 

All can be used with or without hearing aids or a 

cochlear implant. ALD systems for large facilities 

include hearing loop systems, frequency-modulated 

(FM) systems, and infrared systems.

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Hearing loop (or induction loop) systems use 

electromagnetic energy to transmit sound. A hearing 

loop system involves four parts: 

• A sound source, such as a public address system,

microphone, or home TV or telephone

• An amplifier

• A thin loop of wire that encircles a room or branches

out beneath carpeting

• A receiver worn in the ears or as a headset

Amplified sound travels through the loop and creates 

an electromagnetic field that is picked up directly by 

a hearing loop receiver or a telecoil (see sidebar), a 

miniature wireless receiver that is built into many hearing 

aids and cochlear implants. To pick up the signal, a 

listener must be wearing the receiver and be within or 

near the loop. Because the sound is picked up directly 

by the receiver, the sound is much clearer, without as 

much of the competing background noise associated 

with many listening environments. Some loop systems 

are portable, making it possible for people with hearing 

loss to improve their listening environments, as needed, 

as they proceed with their daily activities. A hearing 

loop can be connected to a public address system, a 

television, or any other audio source. For those who 

don’t have hearing aids with embedded telecoils, 

portable loop receivers are also available.

FM systems use radio signals to transmit amplified 

sounds. They are often used in classrooms, where the 

instructor wears a small microphone connected to a 

transmitter and the student wears the receiver, which 

is tuned to a specific frequency, or channel. People 

who have a telecoil inside their hearing aid or cochlear 

implant may also wear a wire around the neck (called 

a neckloop) or behind their aid or implant (called a 

silhouette inductor) to convert the signal into magnetic 

signals that can be picked up directly by the telecoil. 

FM systems can transmit signals up to 300 feet and are 

able to be used in many public places. However, because 

radio signals are able to penetrate walls, listeners in one 

room may need to listen to a different channel than 

those in another room to avoid receiving mixed signals. 

Personal FM systems operate in the same way as larger 

scale systems and can be used to help people with 

hearing loss to follow one-on-one conversations.

Infrared systems use infrared light to transmit sound. A 

transmitter converts sound into a light signal and beams 

it to a receiver that is worn by a listener. The receiver 

decodes the infrared signal back to sound. As with FM 

systems, people whose hearing aids or cochlear implants 

have a telecoil may also wear a neckloop or silhouette 

NIDCD Fact Sheet

Assistive Devices for People with Hearing, 

Voice, Speech, or Language Disorders

hearingbalance

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What’s a telecoil?

A telecoil, also called a t-coil, is a coil of wire that 

is installed inside many hearing aids and cochlear 

implants to act as a miniature wireless receiver. It 

was originally designed to make sounds clearer to 

a listener over the telephone. It also is used with 

a variety of other assistive listening devices, such 

as hearing loop (or induction loop) systems, FM 

systems, infrared systems, and personal amplifiers. 

The telecoil works by receiving an electromagnetic

signal from the hearing loop and then turning it

back into sound within the hearing aid or cochlear

implant. This process eliminates much of the

distracting background noise and delivers sound

customized for one’s own need. For people who

are hard-of-hearing who do not have a telecoilequipped hearing aid or cochlear implant, loop

receivers with headsets can provide similar benefits

but without the customized or “corrected sound”

feature that matches one’s hearing loss pattern.

Many cochlear implants have a telecoil built 

into the sound processor, or can use an external 

telecoil accessory with both hearing aidcompatible telephones and public loop systems. 

A simple switch or programming maneuver 

performed by the user activates this function.

See the NIDCD fact sheet Hearing Aids at https://

www.nidcd.nih.gov/health/hearing-aids for more 

information.
Speech-generating devices go one step further by 

translating words or pictures into speech. Some 

models allow users to choose from several different 

voices, such as male or female, child or adult, and 

even some regional accents. Some devices employ a 

vocabulary of prerecorded words while others have 

an unlimited vocabulary, synthesizing speech as words 

are typed in. Software programs that convert personal 

computers into speaking devices are also available.

What augmentative and alternative 

communication devices are available 

for communicating by telephone?

For many years, people with hearing loss have used

text telephone or telecommunications devices, called

TTY or TDD machines, to communicate by phone. This

same technology also benefits people with speech

difficulties. A TTY machine consists of a typewriter

keyboard that displays typed conversations onto

a readout panel or printed on paper. Callers will

either type messages to each other over the system

or, if a call recipient does not have a TTY machine,

use the national toll-free telecommunications relay

service at 711 to communicate. (See the fact sheet 

Telecommunications Relay Services at https://www.

nidcd.nih.gov/health/telecomm for more information.) 

Through the relay service, a communications assistant 

serves as a bridge between two callers, reading typed 

messages aloud to the person with hearing while 

transcribing what’s spoken into type for the person 

with hearing loss.

With today’s new electronic communication devices,

however, TTY machines have almost become a thing

of the past. People can place phone calls through the

telecommunications relay service using almost any

device with a keypad, including a laptop, personal

digital assistant, and cell phone. Text messaging has

also become a popular method of communication,

skipping the relay service altogether.

inductor to convert the infrared signal into a magnetic 

signal, which can be picked up through their telecoil.

Unlike induction loop or FM systems, the infrared 

signal cannot pass through walls, making it particularly 

useful in courtrooms, where confidential information 

is often discussed, and in buildings where competing 

signals can be a problem, such as classrooms or movie 

theaters. However, infrared systems cannot be used in 

environments with too many competing light sources, 

such as outdoors or in strongly lit rooms.

Personal amplifiers are useful in places in which the 

above systems are unavailable or when watching TV, 

being outdoors, or traveling in a car. About the size of a 

cell phone, these devices increase sound levels and reduce 

background noise for a listener. Some have directional 

microphones that can be angled toward a speaker or 

other source of sound. As with other ALDs, the amplified 

sound can be picked up by a receiver that the listener is 

wearing, either as a headset or as earbuds. 

What types of augmentative and 

alternative communication devices 

are available for communicating 

face-to-face?

The simplest AAC device is a picture board or touch 

screen that uses pictures or symbols of typical items 

and activities that make up a person’s daily life. For 

example, a person might touch the image of a glass to 

ask for a drink. Many picture boards can be customized 

and expanded based on a person’s age, education, 

occupation, and interests. 

Keyboards, touch screens, and sometimes a person’s 

limited speech may be used to communicate desired 

words. Some devices employ a text display. The display 

panel typically faces outward so that two people can 

exchange information while facing each other. Spelling 

and word prediction software can make it faster and 

easier to enter information. 

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Another system uses voice recognition software and 

an extensive library of video clips depicting American 

Sign Language to translate a signer’s words into text or 

computer-generated speech in real time. It is also able to 

translate spoken words back into sign language or text.

Finally, for people with mild to moderate hearing loss, 

captioned telephones allow you to carry on a spoken 

conversation, while providing a transcript of the other 

person’s words on a readout panel or computer screen 

as back-up.

What types of alerting devices 

are available?

Alerting or alarm devices use sound, light, vibrations, 

or a combination of these techniques to let someone 

know when a particular event is occurring. Clocks and 

wake-up alarm systems allow a person to choose to 

wake up to flashing lights, horns, or a gentle shaking. 

Visual alert signalers monitor a variety of household 

devices and other sounds, such as doorbells and 

telephones. When the phone rings, the visual alert 

signaler will be activated and will vibrate or flash a 

light to let people know. In addition, remote receivers 

placed around the house can alert a person from any 

room. Portable vibrating pagers can let parents and 

caretakers know when a baby is crying. Some babymonitoring devices analyze a baby’s cry and light up a 

picture to indicate if the baby sounds hungry, bored, 

or sleepy. 

What research is being conducted 

on assistive technology?

The National Institute on Deafness and Other 

Communication Disorders (NIDCD) funds research into 

several areas of assistive technology, such as those 

described below. 

• Improved devices for people with hearing

loss NIDCD-funded researchers are developing

devices that help people with varying degrees of

hearing loss communicate with others. One team

has developed a portable device in which two or

more users type messages to each other that can

be displayed simultaneously in real time. Another

team is designing an ALD that amplifies and

enhances speech for a group of individuals who

are conversing in a noisy environment.

• Improved devices for nonspeaking people

w More natural synthesized speech

NIDCD-sponsored scientists are also developing

a personalized text-to-speech synthesis system

that synthesizes speech that is more intelligible

and natural sounding to be incorporated in

speech-generating devices. Individuals who are

at risk of losing their speaking ability can

prerecord their own speech, which is then

converted into their personal synthetic voice.

w Brain–computer interface research

A relatively new and exciting area of study

is called brain–computer interface research.

NIDCD-funded scientists are studying how

neural signals in a person’s brain can be

translated by a computer to help someone

communicate. For example, people with

amyotrophic lateral sclerosis (ALS, or Lou

Gehrig’s disease) or brainstem stroke lose their

ability to move their arms, legs, or body. They

can also become locked-in, where they are not

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NIDCD Fact Sheet

Assistive Devices for People with Hearing, 

Voice, Speech, or Language Disorders

hearingbalance
Where can I get more information?

The NIDCD maintains a directory of organizations

that provide information on the normal and

disordered processes of hearing, balance, taste, smell,

voice, speech, and language. Please see the list of 

organizations at https://www.nidcd.nih.gov/directory.

Use the following keywords to help you search for

organizations that can answer questions and provide

printed or electronic information on assistive devices:

• Assistive technology

• Assistive listening device

• Augmentative and alternative

communication

For more information, additional addresses and phone 

numbers, or a printed list of organizations, contact:

NIDCD Information Clearinghouse

1 Communication Avenue

Bethesda, MD 20892-3456

Toll-free Voice: (800) 241-1044

Toll-free TTY: (800) 241-1055

Fax: (301) 770-8977

E-mail: nidcdinfo@nidcd.nih.gov

able to express words, even though they are 

able to think and reason normally. By implanting 

electrodes on the brain’s motor cortex, some 

researchers are studying how a person who is 

locked-in can control communication software 

and type out words simply by imagining the 

movement of his or her hand. Other researchers 

are attempting to develop a prosthetic device 

that will be able to translate a person’s thoughts 

into synthesized words and sentences. Another 

group is developing a wireless device that 

monitors brain activity that is triggered by 

visual stimulation. In this way, people who are 

locked-in can call for help during an emergency 

by staring at a designated spot on the device.

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NIDCD supports and conducts research and research training on the 

normal and disordered processes of hearing, balance, smell, taste, 

voice, speech, and language and provides health information, based 

upon scientific discovery, to the public.

hearing, balancesmell, tastevoice, speech, language

NIDCD Fact Sheet: Assistive Devices for People with 

Hearing, Voice, Speech, or Language Disorders 

NIH Publication No. 11-7672

December 2011

For more information, contact:

NIDCD Information Clearinghouse

1 Communication Avenue

Bethesda, MD 20892-3456

Toll-free Voice: (800) 241–1044

Toll-free TTY: (800) 241–1055

Fax: (301) 770–8977

E-mail: nidcdinfo@nidcd.nih.gov

Internet: https://www.nidcd.nih.gov

The NIDCD Information Clearinghouse is a service of the

National Institute on Deafness and Other Communication 

Disorders, National Institutes of Health, U.S. Department 

of Health and Human Services.

NIH. . .Turning Discovery Into Health

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