Glossary
Augmentative and alternative communication (AAC)
Augmentative and alternative communication (AAC) is a clinical practice area that supplements or compensates for impairments in speaking or understanding language. It uses tools such as picture boards, letter boards and speech-generating devices, and it is augmentative when used alongside speech and alternative when used instead of speech.
Updated October 16, 20264 cited facts, each traced to its source
Also called AAC.
Augmentative and alternative communication (AAC) is the set of methods and tools that help a person communicate when speech alone does not work for them. The American Speech-Language-Hearing Association defines it as an area of clinical practice that supplements or compensates for impairments in speech-language production or comprehension 1. AAC covers spoken and written modes of communication, and it includes low-tech tools as well as electronic devices.
AAC is augmentative when it supplements speech and alternative when it replaces speech
The two words describe how a tool is used. ASHA says AAC is augmentative when used to supplement existing speech, and alternative when used in place of speech that is absent or not functional 2. A person who can speak a few words and points to a picture board to add detail is using AAC augmentatively. A person who cannot speak at all and relies on a device to talk is using it as an alternative.
ASHA's examples run from simple to complex: manual signs, gestures, finger spelling, tangible objects, line drawings, picture communication boards, letter boards and speech-generating devices.
Example: a letter board or a speech-generating device
A young child who cannot yet speak clearly points to pictures on a board to ask for a snack, and a speech-generating device reads out the chosen words. Both are AAC. The board needs no power and can be made from paper, while the device uses a touchscreen or switch and stores a vocabulary of words and phrases. The clinician chooses the tool to match the person's motor skills, vision, language and daily needs.
About 5 million Americans may benefit
ASHA cites an estimate by Beukelman and Light from 2020 that approximately 5 million Americans may benefit from AAC 3. The same page says that the number of people who use AAC is hard to estimate, because needs vary widely. The estimate counts people who may benefit, not people who currently use a device.
Word prediction shows why speed matters for AAC
Speed is a central problem for AAC users. In a 2008 simulation study of AAC communication, an advanced word prediction system gave a 58.6 percent improvement in communication rate over letter-by-letter entry 4. For a typist, word prediction is a convenience. For an AAC user, it can decide how much of their message gets through.
Why it matters for dictation
Dictation depends on speech. A person who cannot speak, or whose speech is hard for a recognizer to follow, cannot dictate in the usual way. For those users, AAC tools and typed input are the practical route, and speech recognition may still help if it is trained on their voice or used on a device that handles atypical speech. The guide on speech recognition for speech impairments covers what recognition can and cannot do for people whose speech differs from typical speech.
Dictation is one of many assistive technologies, and a user may combine several. A person with a motor disability may use voice input for text and AAC for conversation, so the two should be planned together.
Related terms
- Dysarthria: a speech disorder caused by weakness or poor control of the muscles used to speak, which is one reason people use AAC.
- Assistive technology: the broad category of tools, including AAC, that help people with disabilities.
- Dictation: speaking text into a computer, which needs speech that the recognizer can follow.
Guides that cover it
- Speech recognition for stuttering and dysarthria
- Speech to text for accessibility: the full overview
- ASHA's practice portal page on AAC, the professional source for this definition
Evidence
Every number on this page, with where it comes from. Open a fact to see the exact words in its source.
- 1.The American Speech-Language-Hearing Association defines augmentative and alternative communication as an area of clinical practice that supplements or compensates for impairments in speech-language production or comprehension, including spoken and written modes of communication.
American Speech-Language-Hearing Association, ASHA Practice Portal, n.d. · Original
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Related terms
- Speech to Text for Accessibility, RSI and DisabilitiesThe topic this term belongs to
- Access to WorkAccess to Work is a UK government grant for people with a disability or health condition who need support to do their job. GOV.UK says it can help pay for specialist equipment and assistive software, among other support, and that the grant does not affect other benefits and does not have to be paid back.
- Assistive technology (AT)Assistive technology (AT) is any item, piece of equipment or product system that increases, maintains or improves what a person with a disability can do. Speech recognition, voice control and screen readers are common examples.
- CART captioningCART captioning is a live text service in which a trained captioner types what is said, usually on a stenotype machine, and the words appear on a screen as they are spoken. CART stands for Communication Access Realtime Translation, and it is also called real-time captioning.
- De Quervain's tenosynovitisDe Quervain's tenosynovitis is a painful condition in which tendons that move the thumb become irritated where they pass through a narrow tunnel on the thumb side of the wrist. Repeated thumb and wrist movements, such as texting, can worsen it.
- Disabled Students' Allowance (DSA)Disabled Students' Allowance (DSA) is UK government support for students with a disability, mental health problem or long-term illness, to cover study costs that come from the condition. It depends on individual needs rather than household income, and it does not have to be paid back.
- DysarthriaDysarthria is a speech disorder that happens when brain or nerve damage changes the way the muscles used for speaking work, so speech can sound slow, slurred or hard to understand. Speech recognition trained on typical voices can make more errors with this speech, so accuracy depends on the person and the software.
- DysgraphiaDysgraphia is a difficulty with writing that does not match a person's cognitive level and age, even after adequate instruction. It can affect letter formation, spacing, spelling, writing speed and composition, and speech to text lets a person get their words onto the page without writing each letter by hand.
- Individualized Education Program (IEP)An Individualized Education Program (IEP) is a written statement for a child with a disability, developed, reviewed and revised under the federal IDEA regulations. For US students, it is the school's plan for the special education and services the child needs, and the team must consider whether the child needs assistive technology.
- Median nerveThe median nerve is one of the main nerves of the arm. It runs from the forearm through the wrist into the hand, giving feeling and movement to parts of the hand.
- Reasonable accommodationA reasonable accommodation is a change to the job, the workplace or the equipment that lets a qualified person with a disability do the work. Under U.S. law, employers with 15 or more employees must provide one unless it would impose an undue hardship.
- Repetitive strain injury (RSI)Repetitive strain injury (RSI) is an umbrella term for pain and damage to muscles, tendons and nerves that builds up from repeated movements, held postures or sustained effort, felt in the hands, wrists, arms, shoulders and neck.
- Screen readerA screen reader is software that reads what is on a computer or phone screen aloud, or sends it to a braille display, so that people who are blind or have low vision can use the device. The most used screen readers on Windows are JAWS and NVDA, and VoiceOver is the one built into Apple devices.