Does AAC Delay Speech? What the Evidence Shows

What AAC actually means

Augmentative communication adds to speech. Alternative communication offers another route when speech is unavailable or not sufficient. AAC may be temporary, long-term, or used differently in different situations. It is not one particular device or therapy program. [1] [2]

A child who has a few spoken words may still need AAC to say more, communicate with unfamiliar people, or be understood when speech is difficult. Having some speech does not make AAC inappropriate. [2]

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Children can use any combination of these forms without having to work through them in order. ASHA calls this multimodal communication: using the combination that works for the child, the people they communicate with, and the situation. A child may use a sign at home, point to a picture in childcare, and speak a word in the same afternoon. [1] [2]

Speech and language are also different. AAC can provide a way to express language without requiring the same movements used to speak. Choosing AAC does not, by itself, explain why a child has limited speech. For more on how clinicians assess that question, see Speech Delay vs. Autism: How Clinicians Tell the Difference. [1] [9]

What research shows about AAC and speech

Across the studies reviewed here, AAC has not been shown to suppress speech. That is reassuring if you are worried about holding your child's speech back. The studies involved different groups of children and adults, using different forms of support, so they cannot tell us that every method will work for every child or that every AAC user will eventually speak. [4] [5] [6] [7]

Older reviews: modest speech gains, with small studies

A 2006 review by Diane Millar, Janice Light, and Ralf Schlosser identified 23 studies involving 67 people with developmental disabilities. Seventeen studies lacked experimental control. Its best-evidence analysis used six studies with 27 cases, largely involving intellectual disability or autism. The review described participants ages 2–60 and interventions involving manual signs or nonelectronic aided systems. None of those 27 cases showed decreased speech production; most showed gains, generally modest. This was not a toddler-only study of modern electronic devices. Only the abstract was checked for this article. [4]

A 2008 review by Schlosser and Oliver Wendt focused on children with autism or what was then called pervasive developmental disorder–not otherwise specified. It included nine single-subject studies with 27 participants and two group studies with 98 participants. Most studies reported increased speech production, but gains were modest and cannot predict what will happen for one child. The abstract and ASHA's evidence summary were checked, not the full review. [5]

A 2021 update by Emily White and colleagues included 25 single-case articles and three group-design articles published through May 2020. Overall, speech production improved, but speech gains did not surpass AAC use. ASHA's summary notes small effects on speech production in more than half of the studies. For families, this means AAC may remain useful even as a child begins to say more words. The abstract and ASHA evidence summary were checked, not the full review. [5] [7]

These reviews overlap: the 2021 review explicitly updates the 2008 review. Their study counts cannot be added up as independent replications or converted into a child's chance of speaking. [5] [7]

A randomized toddler trial: AAC with parent coaching

In a 2010 trial, MaryAnn Romski and colleagues randomly assigned 68 toddlers with developmental delays and fewer than 10 spoken words to three parent-coached interventions: augmented communication input, augmented communication output, or spoken communication. Sixty-two children completed the intervention. [6]

The augmented groups used both augmented and spoken target words and had substantially larger vocabulary sizes than the spoken-communication group. The authors concluded that augmented language intervention with parent coaching had a positive communication effect and did not hinder speech. [6]

These toddlers had developmental delays; the study was not limited to autistic toddlers. Researchers measured vocabulary from transcripts of the 18th and 24th intervention sessions, recording the target words children used. That tells us about communication during those sessions, but it does not establish how children used those skills at home, at school, or in the community. Only the abstract was checked. [6]

An autism trial: school-aged children, not toddlers

Connie Kasari and colleagues studied 61 autistic children ages 5–8 who were minimally speaking. Children received a blended play-based developmental/behavioral communication intervention, initially with or without a speech-generating device. Treatment was adjusted based on children's early responses over six months, with a three-month follow-up. Both groups received professional support, so the study tested the device as part of that intervention. [8]

Starting with the device integrated into that intervention led to better outcomes in spontaneous communicative utterances, different words, and comments at the 24-week endpoint. The main measure counted both spoken and device-produced utterances; an additional analysis restricted to spoken utterances still favored starting with the device. [8]

The outcomes were measured in standardized naturalistic play samples with an adult, not a survey of every conversation in daily life. Some between-group advantages weakened by follow-up. The study enrolled fewer children than planned and had specific entry criteria, including a receptive-language age equivalent of at least 24 months. Those research eligibility criteria are not prerequisites for offering AAC in practice. Nor can results in 5–8-year-olds simply be applied to infants and toddlers. [1] [2] [8]

What should count as progress?

Speech can be one of several goals in an AAC plan. ASHA describes AAC intervention as supporting everyday communication and participation. Its early-intervention guidance includes asking, refusing, getting attention, and commenting, as well as naming objects. [1] [3]

For a family, the goal might be more specific than “more language”: a child can tell someone to stop, ask for help opening a container, greet a sibling, or comment on something funny. These are practical examples of the communication functions ASHA describes, not promised outcomes from a particular treatment. [3]

Ask the team to track how independently, with whom, and where communication happens. Choosing a symbol after a therapist's prompt tells you something different from sending a message at home without help, and speech needs to be tracked separately too. Alongside the specific skills measured in therapy, ask how your child is communicating with the people they spend time with every day. [1] [6] [8]

Do not interpret a shift between modes as failure by itself. Multimodal communication means the available routes can vary with context and need. Continue paying attention to speech, but do not remove a working communication route merely because speech is the hoped-for outcome. [1] [2]

Does a child need to be “ready” for AAC?

ASHA says there are no prerequisites for AAC intervention. Its National Joint Committee guidance explicitly includes age, cognitive, linguistic, and motor prerequisites; its early-intervention guidance says there is no “too young” age. [1] [2] [3]

Finding an accessible system still takes care. A child may need larger symbols, another way to select a message, different positioning, or support for vision, hearing, and movement. An assessment helps identify those needs and gives the team a chance to try possible solutions. ASHA describes selection through touch, eye gaze, switches, or partner-assisted scanning, so a child does not have to be able to point with a finger. [1] [2]

Children and the people who communicate with them may need ongoing teaching and adjustments as they learn to use AAC. That support can begin while a child is still developing skills. A child should not have to prove a certain IQ, imitate speech, or demonstrate perfect symbol use before anyone considers an accessible communication system. [1] [2] [3]

Getting support without turning it into a shopping decision

You can start the conversation with an SLP before you know which tools might help: “My child cannot reliably communicate what they need or want to share. Can we assess AAC alongside speech and language?”

An SLP's assessment should consider the child's current ways of communicating; understanding and expression; vision, hearing, and motor access; the people and places involved; family priorities; and the languages used at home. ASHA describes AAC assessment as ongoing: a system can be tried and refined rather than chosen once forever. [1] [2]

Ask for a plan that includes:

1. Useful communication now, including low-tech or interim supports while a fuller assessment is arranged. ASHA's early-intervention guidance supports beginning with functional options rather than leaving a child without communication. [2] [3]
2. A chance to try suitable options. If your child needs help accessing a system, SLPs can collaborate with occupational or physical therapists, vision specialists, and assistive-technology professionals as appropriate. [1] [3]
3. Partner coaching, so caregivers and childcare or school staff know how to model and respond. [1] [3]
4. Relevant language and vocabulary. AAC should support the languages and relationships the child actually uses; ask how the system will work with family members who speak different languages. [1]
5. A written access and funding plan. Coverage for speech-generating devices varies, and a comprehensive evaluation may be needed. Ask who handles trials, paperwork, training, repairs, and a backup when equipment is unavailable. [1]

For U.S. children under 3, families can contact their early-intervention program directly without a doctor's referral to ask about evaluation. Eligibility is determined through the program; requesting help does not guarantee a specific service or device. At age 3 and older, contact the local school district about evaluation. [10]

How to get early intervention services

Hearing and developmental assessment can proceed alongside communication support. If your child loses words or other developmental skills they previously had, contact their healthcare provider promptly, even if you are already adjusting their AAC support. [9]

What caregivers can do while learning the system

These are practical applications of ASHA guidance, not a prescription for a particular child or a substitute for individualized coaching. [1] [3]

• Model rather than test. If the child's system has an appropriate symbol, point to it while saying the word during an ordinary routine. ASHA calls this aided language modeling or augmented input. For example, model “go” during play rather than repeatedly asking the child to identify it. Ask the SLP to demonstrate with your child's system. [1] [3]
• Make communication available. ASHA states that people who use AAC should always have access to their tools. Plan for play, meals, childcare, and outings, including what to use if equipment stops working. A paper backup can be part of that plan. [1] [3]
• Respond to the message across modes. Notice a gesture, sound, sign, picture, spoken word, or device message instead of insisting that only one form counts. That follows AAC's multimodal purpose. [1] [2]
• Include more than requests. Model messages for help, refusal, greeting, and shared enjoyment, not only asking for food or toys. ASHA's guidance includes these broader communication functions. [1] [3]
• Keep access unconditional. Do not withhold food, water, comfort, toileting, or the communication system to make a child speak or select a symbol. This is a practical safety boundary grounded in the right to communicate. [1] [2]

You do not need to turn every family moment into a session. Ask the team for a small, workable routine to practice together and a way to report what is and is not working. ASHA recommends caregiver coaching within everyday routines. [3]

Frequently asked questions

The bottom line

If you are considering AAC for your child, the research reviewed here offers reassurance: it does not support withholding AAC out of fear that it will hold speech back. You can continue supporting speech while helping your child communicate now. A plan should fit your child and include coaching for the people who use AAC with them, with realistic expectations about speech development. [1] [2] [3] [4] [5] [6] [7] [8]

If you are also looking for answers about your child's development, our guides to early autism signs and speech delay versus autism explain how communication support and assessment can move forward together.