Augmentative and alternative communication (AAC) is any method a person uses to communicate other than speech, ranging from key word sign and communication boards to speech-generating devices. The evidence indicates AAC supports people with complex communication needs and does not delay or replace spoken language; reviews show it may modestly increase speech. The NDIS funds AAC as assistive technology when a speech pathologist provides written evidence that it is reasonable and necessary.
Key takeaways
- AAC covers unaided methods (gesture, key word sign) and aided methods (PODD communication books, speech-generating devices, AAC apps on tablets).
- Current systematic reviews find AAC does not impede speech and may support modest gains in spoken language; it is not a "last resort".
- The NDIS funds AAC under assistive technology, with the evidence required scaling by cost tier (under $1,500, $1,500–$15,000, and over $15,000).
- A speech pathologist's assessment and written recommendation are central to a successful AAC funding request.
- No single AAC system suits every situation; most people use a combination across different settings and partners.
What is AAC, and who is it for?
AAC is any communication method used to augment or replace natural speech for people with complex communication needs. According to , AAC is "when a person uses something other than speech to communicate". Complex communication needs describe a significant communication disability that can arise from a range of physical, sensory, cognitive, or developmental causes and that restricts everyday participation.
AAC may be relevant for people with conditions such as cerebral palsy, autism, intellectual disability, Down syndrome, motor neurone disease, acquired brain injury, or stroke. It is used by children developing language and by adults who have lost speech, and it can be permanent or temporary depending on the person's needs.
What are the main types of AAC?
AAC is grouped into unaided and aided systems, and most people use both. Speech Pathology Australia describes the categories this way:
Key word sign is an unaided method in which families and communication partners are supported to sign the key words in a spoken sentence. PODD (Pragmatic Organisation Dynamic Display) is a low-tech aided system of communication books organised by the purpose of a message — for example, separate pathways for asking a question, telling a story, or saying something is wrong. describes PODD as an organised language system with navigation pathways based on the purpose of the message, used to support language development across childhood and increasingly by adults. A speech-generating device is an electronic device on which a person selects symbols or text to produce a spoken message.
Speech Pathology Australia notes that one system is rarely enough: people "often need both high technology systems, low technology systems and unaided AAC depending on where they are and with whom they are communicating".
Does AAC delay or stop speech?
No — the current evidence does not support the long-standing myth that AAC prevents or delays speech. This concern is one of the most common reasons families hesitate to start AAC, but multiple systematic reviews have looked specifically at speech production outcomes and found the opposite pattern.
A widely cited systematic review by examined the effects of AAC intervention on speech production in children with autism. Across 11 studies (nine single-subject designs with 27 participants and two group studies with 98 participants — 125 participants in total), the review concluded that AAC interventions do not impede speech production, and most studies documented increases in speech output. Importantly, the authors cautioned that these gains were modest rather than dramatic, and recommended clinicians hold realistic expectations.
The practical implication is that introducing AAC does not mean "giving up" on speech. Providing a reliable way to communicate now supports a person's participation, reduces frustration, and may, for some people, accompany growth in spoken language over time. Outcomes vary between individuals, and AAC should be framed as one part of a broader communication plan rather than a guaranteed pathway to any specific result.
How does the NDIS fund AAC?
The NDIS funds AAC under assistive technology (AT), and the evidence required depends on the cost and risk of the item. The as equipment or devices that help a person do something they could not otherwise do, or do it more easily or safely. Communication devices and AAC systems sit within this category.
The NDIS sets three AT cost tiers, each with a different evidence pathway:
These tiers and evidence requirements are set out on the NDIS pages for and how to . Many AAC solutions — for example a tablet configured with an AAC app and a protective case, or a dedicated speech-generating device — fall into the mid-cost or high-cost tiers, which means written clinical evidence from a is generally needed.
What does the NDIS look for in an AAC request?
The NDIS must be satisfied that the AAC is reasonable and necessary before it can be funded. Under the NDIS framework, supports must relate to the person's disability, represent value for money, and be effective and beneficial, among other criteria — these are the . For AAC, a speech pathology assessment usually documents:
- the person's communication strengths, needs, and complex communication needs;
- the AAC trial — which systems were tried and how the person responded;
- the functional impact: how the recommended device supports participation in daily life and progress toward the person's goals;
- why the specific device is value for money compared with alternatives; and
- training and support needs for the person and their communication partners.
When deciding whether a support is effective and beneficial, the and whether there is evidence the support works for people with similar needs — which is why citing the evidence base for AAC in a report matters.
Evidence at a glance
- — across 11 studies and 125 participants, AAC intervention did not impede speech production in children with autism and most studies showed increased speech output, though gains were modest.
- — defines AAC, aided and unaided systems, key word sign, and speech-generating devices, and notes most people need a combination of systems.
- — describes PODD as an organised language system used to support communication and language development.
- and — set out the AT cost tiers (under $1,500, $1,500–$15,000, over $15,000) and the evidence required at each tier.
- — outlines the criteria a support must meet, including value for money and being effective and beneficial.
Frequently asked questions
Will using AAC stop my child from learning to speak?
No. Systematic review evidence, including , indicates AAC does not impede speech production and may be associated with modest increases in speech. AAC gives a reliable way to communicate now, which supports participation regardless of how spoken language develops. Outcomes differ between individuals.
Is an iPad with an app considered AAC, and will the NDIS fund it?
Yes, a tablet configured specifically with an AAC app can be an aided high-tech AAC system. The NDIS may fund it as assistive technology when a speech pathologist provides written evidence that it is reasonable and necessary. Whether a formal assessment is needed depends on the of the device and configuration.
What evidence does the NDIS need for an AAC device?
It depends on cost. Low-cost, low-risk items under $1,500 may not need formal evidence; mid-cost items ($1,500–$15,000) need written evidence from an allied health practitioner; high-cost items over $15,000 need an assessment report from a qualified AT assessor, per the .
Who assesses someone for AAC?
A speech pathologist assesses communication and recommends AAC, often trialling several systems before recommending one. may contribute on access, seating, and positioning so a person can physically use a device. Communication partners are also supported to use the chosen system.
Does AAC work for adults, not just children?
Yes. AAC is used across the lifespan, including by adults with acquired conditions such as stroke, motor neurone disease, or brain injury. Speech Pathology Australia notes systems such as PODD are increasingly used by adults as well as children.
Align Network's speech pathologists and occupational therapists assess communication needs, trial AAC systems, and prepare the evidence the NDIS requires for assistive technology. To discuss AAC for yourself or someone you support, speak with Align Network's speech pathology and occupational therapy team via our .
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