Summary
- In the studies reviewed here, speech didn't go down after AAC was introduced. Speech gains were usually small.
- There are no skills a person has to show before starting.
- Research supports adults pointing to words on the device while they talk ("modeling").
- In one four-year study, 96 percent of people with ALS who were offered AAC accepted it.
- People who use AAC want voices that match their age and identity.
Research on AAC goes back decades, and much of it uses small studies that follow a few people closely. We rely mostly on reviews that combine those studies. Sources are listed at the bottom of the page.
Does AAC stop people from talking?
A 2006 research review found that, in its most rigorous studies, none of 27 people lost speech after AAC was introduced, 11 percent showed no change, and 89 percent gained some speech. The gains were mostly modest.1 Reviews focused on autistic children reached the same conclusion in 2008 and again in 2021: AAC does not impede speech, and is linked to small improvements.23
In a randomized trial of 68 toddlers with fewer than 10 spoken words, children whose parents were coached to use a speech-generating device learned many more words, including spoken words, than children taught with speech alone. The authors concluded AAC "does not hinder, and actually aids" speech.4
Introducing AAC did not reduce speech in these studies. They can't predict whether an individual child will learn to talk.
Does someone need to be "ready" for AAC?
ASHA, the US professional body for speech-language pathologists, says: "There are no prerequisites for AAC intervention."5 An analysis of 114 studies reported similar benefits across the ages, diagnoses and starting skills it examined.6 In a trial with minimally verbal autistic children aged 5 to 8, the children made faster gains in spoken language when their therapy included a speech-generating device from the start.7
Using AAC while you talk (modeling)
Modeling means pointing to words on the person's AAC system as you talk to them. A meta-analysis found this "highly effective" for both understanding and expression, across ages, disabilities and language levels.8 A review of 48 studies with children came to a similar conclusion.9 Our guide to modeling shows how.
Autism
An estimated 30 percent of autistic children remain minimally verbal at school age.10 A review of high-tech AAC, including tablets and apps, found communication benefits for people with intellectual and developmental disabilities, including autism.11 A review of autistic teenagers and adults found benefits too, and called for more research with those age groups.12 AAC for autistic children · autistic adults.
Cerebral palsy, Down syndrome and apraxia
- Cerebral palsyAbout 1 in 4 children with cerebral palsy cannot talk.13 A systematic review found moderate-quality evidence that AAC improves both understanding and expression.14 More.
- Down syndromeA review of 13 studies found AAC tools, most often speech-generating devices and picture exchange, increased interaction with peers and supported quality of life and self-esteem.15 More.
- Childhood apraxia of speechA review of 11 studies describes AAC used alongside speech therapy, and suggests starting early may help.16 More.
ALS and MND
Most people with ALS eventually can't meet daily communication needs with speech; estimates range from 80 to 95 percent.17 In a four-year study, 96 percent of participants accepted AAC, and everyone who started using it continued.18 People with MND who bank their voice say the main reason is to preserve their identity.19 In a comparison by 831 listeners of voices banked by people with ALS, those made with neural networks were clearer, more natural and preferred over older methods.20 AAC for ALS and MND.
Stroke, Parkinson's, cancer and intensive care
- Stroke and aphasiaAbout 1 in 3 people who have a stroke have aphasia, a language difficulty.21 Speech and language therapy helps,22 and high-tech AAC is a useful way to communicate alongside it.23 More.
- Parkinson'sSpeech changes have been reported in as many as 89 percent of people with Parkinson's, yet only 3 to 4 percent receive speech treatment.24 More.
- LaryngectomyPeople facing removal of the voice box describe losing their voice as the most feared consequence of surgery. In one program, recording a voice beforehand was demanding enough that many didn't finish, but those who used their personalised voice kept using it.25 More.
- Intensive carePatients on ventilators who find it harder to communicate feel more distress, and those with more ways to communicate feel less fear and anger.26 A review found computer-based aids among the methods that helped ventilated patients communicate.27 More.
Speed and voice
People speak at roughly 125 to 185 words per minute. Communicating with AAC is far slower: around 2 words per minute with switch scanning and 8 to 10 by pointing, according to figures cited in one review.28 Eye-gaze typing is usually under 10 words per minute.29 In one line of research, pre-stored whole sentences raised both conversation speed and how competent listeners judged the AAC user to be.30
On voices: children and families want synthetic voices that match a child's age and background, though being easy to understand comes first.31 People with MND said preserving their identity was their main reason for banking their voice.19
How many people could benefit?
A UK study estimated that about 0.5 percent of the population, or 536 people in every 100,000, could benefit from AAC, most of them with one of nine conditions including dementia, Parkinson's, autism, stroke, cerebral palsy and MND.32 A widely used textbook estimates about 5 million Americans and 97 million people worldwide.33
About these summaries
Many AAC studies are small, and research on adults with Parkinson's, MS and apraxia is especially thin, and we note that on those pages. No study here tested Dawn. If you spot an error, please tell us at [email protected]. Read more about how we write these pages.