Last updated 2026-07-11
TL;DR
Feature matching starts with the child, never the device. You profile a child's motor, language, sensory, and cognitive abilities first, then compare those abilities to the technical features of candidate AAC systems. No single test produces a recommendation. The match gets built across several sessions and real-world settings, ideally with a speech-language pathologist who has AAC experience.
What is feature matching in AAC, and why does it matter?
Feature matching is the core method the AAC field uses to select communication systems. You don't start with a product and ask whether the child can use it. You start with the child and ask which system features line up with what that child actually does, sees, hears, and needs to say.
The American Speech-Language-Hearing Association defines feature matching as "the process of comparing an individual's abilities and needs to the characteristics or features of AAC systems and devices." [1] That sounds simple. In practice it means building a detailed picture of a child across several domains before a single device is ever demoed.
Why does this matter so much? Because device abandonment is real. Research published in the journal Augmentative and Alternative Communication documents wide-ranging abandonment rates, with some studies reporting that roughly a third of device users give up on their systems, often because the device was picked without enough attention to the user's daily environment, motor access, or vocabulary needs. [2] Feature matching is the field's best answer to that problem.
This is not a test you administer on a Tuesday morning. It unfolds across observations, trials, and conversations with the people who know the child best.
Who should lead a feature matching assessment?
A speech-language pathologist with documented AAC experience should lead the process. ASHA's scope of practice for SLPs includes augmentative and alternative communication evaluation and intervention. [3] SLPs vary widely in their AAC training, though, so ask a prospective evaluator how many AAC evaluations they complete per year and whether they have access to a device lending library or trial systems.
For children with complex motor needs, like those with cerebral palsy or childhood apraxia of speech, an occupational therapist or physical therapist often joins the team to assess seating, positioning, and upper-limb access. Vision specialists matter too if there's any question about field of vision or tracking.
Parents are not passive observers here. You're the expert on your child's stamina, frustration patterns, what motivates them, and what their day actually looks like. A good team treats family knowledge as data, not background noise.
Some families pursue an AAC evaluation through their school district under IDEA, which entitles eligible students to assistive technology evaluations at no cost to the family. Others go through private clinics or children's hospitals. Insurance funding often requires a physician referral and a letter of medical necessity, and the evaluation report itself usually becomes the primary documentation for funding approval.
What do you assess before looking at any device?
This is the part most families don't know about. Feature matching does not start with devices. It starts with a detailed profile of the child across several domains.
Language and communication. What communicative functions does the child already use (requesting, protesting, commenting, answering)? What modalities do they use (gesture, vocalization, eye gaze, existing symbols)? What's their receptive language level? Do they have echolalia (see our article on echolalia for what that means for AAC selection)?
Cognitive and linguistic features. Can the child match symbols to referents? Do they understand cause and effect? Can they categorize? These abilities tell you whether a system with deep vocabulary organization will work or whether a simpler layout is a better starting point.
Sensory and perceptual abilities. Visual acuity, visual field, contrast sensitivity, and hearing all affect which display types and symbol sizes will be usable. A child with cortical visual impairment may do better with high-contrast, low-density displays even if cognitively they could handle more complex layouts.
Motor abilities. How does the child access their environment? Can they point with a finger? Do they have reliable hand control? Would they benefit from a keyguard, a head pointer, eye gaze, or partner-assisted scanning? Motor access assessment often decides more about device selection than anything else.
Environmental and participation factors. Where does the child spend their day? Who are their primary communication partners? What activities matter most to them? A system that works great in a therapy room but falls apart at the playground or in a noisy classroom is the wrong system.
All of this gets documented before any device is placed in front of the child.
What are the key AAC system features you're actually matching to?
Once you have the child profile, you compare it to specific, concrete features of AAC systems. Here's how the main feature categories map to assessment findings.
| Feature category | What you're assessing | Example match |
|---|---|---|
| Vocabulary organization | Semantic, activity-based, or core/fringe? | Child uses early language = core vocabulary board |
| Symbol type | Objects, photos, line drawings, text? | Child matches photos but not line drawings = photo-based system |
| Display size and layout | Number of items per page, icon size | Low vision = large display, high contrast, 9 or fewer cells per page |
| Access method | Direct touch, scanning, eye gaze, head tracking | No reliable pointing = explore scanning or eye gaze |
| Speech output | Digitized (recorded) vs. synthesized (text-to-speech) | Literacy emerging = synthesized preferred for generalization |
| Portability and durability | Weight, case, water resistance | Active child, outdoor time = ruggedized, lighter device |
| Customization | Can vocabulary be added or reorganized? | Growing child = high customizability needed |
| Partner dependency | Independent use vs. aided input required | Beginning AAC user = assess whether partner will do aided language input |
This table is not exhaustive. Systems also differ in their internal symbol libraries, the language levels built into preprogrammed pages, and their software ecosystems. Some run on dedicated devices. Others are apps on commercial tablets. Neither category is inherently better. The match is what matters. [1]
For children with apraxia of speech, motor speech differences heavily influence which access method and which output type (digitized vs. synthesized) will give the child the most independence.
How do you actually run the trial phase?
After you've narrowed candidates based on the child's profile, you trial the top two or three systems with the child directly. Trials should last long enough to mean something, usually two to four weeks per system in everyday settings, not a single clinic visit.
During trials, the SLP or family observes and records several things: how quickly the child locates vocabulary, how often they initiate versus respond only, whether error rates drop over time, and how the child's communication partners interact with the system. You're also watching for fatigue, frustration, and whether the child reaches for the device on their own.
Many states and AAC vendors run device loan programs built for exactly this phase. ASHA maintains a list of state assistive technology programs, most of which are federally funded under the Assistive Technology Act and offer device lending at no cost. [4] Ask your SLP about this before you pay a cent out of pocket for a trial device.
Data collection during trials doesn't have to be elaborate. A simple tally sheet tracking initiations, vocabulary used, and access errors across 10 to 15 minute sessions gives you enough to compare systems honestly. Your SLP guides this, but parents and teachers can do the observation.
If a child has been in early intervention, those prior records, especially existing communication assessments, are useful context for the trial phase and should travel with the child's file.
What does 'no prerequisites for AAC' actually mean in practice?
Some professionals, and unfortunately some school-based teams, still tell families that a child has to demonstrate cognitive or language skills before they can have AAC. Current evidence does not support that, and neither does ASHA.
ASHA's position states that "Individuals of any age, type, or severity of disability may benefit from AAC" and that there are no prerequisite cognitive or language skills required for an AAC trial. [3] The evidence has been building for decades. A frequently cited review in the Journal of Autism and Developmental Disorders found no evidence that symbolic understanding, cognitive ability, or oral language level should be treated as prerequisites. [5]
In practice, "no prerequisites" means you can begin feature matching and AAC trials with a very young child, with a child who has significant cognitive delays, and with a child who is still using pre-symbolic communication. The system you select will look different for each of them. The right to a trial is the same.
If a school team tells you your child isn't ready for AAC, cite ASHA's position directly and request that a formal assistive technology evaluation be completed under IDEA. That request triggers procedural timelines the district has to follow.
How does feature matching differ for children with autism versus other diagnoses?
The process is the same regardless of diagnosis, but the profile that emerges tends to look different for children with autism spectrum disorder compared to, say, children with cerebral palsy or Down syndrome.
Children with autism often have strong visual-spatial processing relative to auditory processing, which means symbol-based and visual supports may be more accessible than auditory prompting systems. Many autistic AAC users also show real strengths in reading or pattern recognition that inform symbol type selection. Echolalia, both immediate and delayed, changes how you think about language representation on a device. If a child's functional communication is largely echoed phrases, an SLP with AAC experience can use that to select vocabulary that builds on what the child already produces.
Sensory sensitivities matter too. Some children find certain device sounds aversive, and that alone can decide whether a system gets used. Volume control, voice type selection, and vibration feedback are all features worth assessing during trials.
Motor profiles in autism vary more than people expect. Some children have excellent fine motor control and can direct-access a densely arranged grid. Others have significant motor planning difficulties consistent with apraxia of speech that affect both spoken output and device access.
The bottom line: autism is not a single AAC profile. Two children with the same diagnosis can end up with completely different feature matches, which is exactly why the process exists.
What does a feature matching report look like, and how is it used for funding?
At the end of a full feature matching assessment, the SLP writes a report. A thorough one includes a summary of the child's communication profile across every assessed domain, the names of systems trialed and the data from each trial, a clear rationale tying the recommended system to the child's specific profile features, and an implementation section covering vocabulary recommendations and training for communication partners.
That report does two jobs. It guides the team in getting the child started with the right system and vocabulary. And it's usually the primary document submitted to insurance or Medicaid for device funding. Medicare and Medicaid have specific coverage categories for speech-generating devices (SGDs); Medicaid coverage for children falls under EPSDT, which in most states requires coverage of medically necessary assistive technology regardless of cost. [6] Private insurance requirements vary by plan and state.
The report should never name a specific brand without explaining why that brand's features match this child's profile. Reports that just say "the child needs a Tobii" or "the child needs a Snap Core system" with no documented rationale are weaker for funding and may not reflect a true feature match.
Schools may use this report to inform an IEP assistive technology goal and may fund a device under IDEA, though there are rules about whether school-funded devices can go home with a child. Families sometimes pursue dual funding (school for educational use, Medicaid for home use) with help from an AAC advocate or specialist.
What are the most common mistakes families see during AAC assessments?
The most common mistake is an assessment that's really just a product demo. A clinician brings in one or two devices, shows the child how they work, watches for twenty minutes, and writes a recommendation. That's not feature matching. That's guessing with props.
Another common problem is assessments that lean too hard on standardized cognitive tests as gatekeeping tools. A child who scores poorly on a nonverbal IQ test in a clinical setting may show very different abilities in their natural environment. Feature matching should include naturalistic observation, more than structured testing.
Families also run into evaluators with limited familiarity with the full range of AAC options, especially low-tech ones. Low-tech AAC (paper-based communication boards, PECS-style systems) gets dismissed as a fallback when it's a legitimate long-term solution for some communicators. Feature matching should put low-tech options in the comparison, more than electronic devices.
Assessment without an implementation plan is incomplete. Knowing which device fits doesn't help if the child's teachers, parents, and aides don't know how to model its use. Aided language input, where communication partners use the device themselves to model language, is one of the best-evidenced strategies for building AAC use, and it belongs in any feature matching report's recommendations. [7]
How do you document progress after the feature match is made?
Selecting a system is the beginning, not the end. After implementation, ongoing data collection tells you whether the match was right and when it needs updating.
The Communication Matrix, developed by Charity Rowland at Oregon Health and Science University, gives families and clinicians a structured way to track communication functions across seven levels from pre-intentional to language use. [8] It's free online and takes about 20 minutes to complete. Run it at baseline and every few months for a clear picture of whether the child's communication is growing.
Specific AAC-use metrics worth tracking: number of different vocabulary items used per session, total utterances initiated (not prompted), message length over time, and whether the child is using the device across multiple environments and with multiple partners. Growth in these numbers is evidence the match is working.
If progress stalls, the first question is almost always about implementation. Is the device charged and accessible throughout the day? Are communication partners modeling with it? Is the vocabulary organized around what the child actually wants to say? Before concluding the device is wrong, most AAC specialists will troubleshoot implementation for several months.
Some children outgrow their initial feature match as their abilities develop. A child who started with low-tech boards may develop the motor control for direct touch on a dynamic display. A child who began with photo-based symbols may develop symbolic understanding that supports line drawings or text. Feature matching is not a one-time event. You revisit it whenever there's a significant change in the child's abilities, environments, or communication needs.
If you want a tool to practice vocabulary and build language between therapy sessions, Little Words has a structured quiz to help families name communication goals and find where a child is starting from.
What should parents ask for when requesting a feature matching evaluation?
When you contact a clinic, school, or insurance plan to request an AAC evaluation, being specific gets you further than a general request.
Ask for a full AAC evaluation using a feature matching approach, direct trial of at least two candidate systems in everyday settings, inclusion of both low-tech and high-tech options in the comparison, a written report with funding rationale, and a plan for training communication partners.
If you're going through a school district under IDEA, put your request in writing and date it. The district's evaluation timeline begins from the date of your written request, typically 60 days under federal guidelines, though state timelines vary. [9] Keep copies of everything.
For families using online speech therapy, confirm that the remote SLP has access to device loan programs and can coordinate with a local team for the physical trial phase. Remote SLPs can contribute to the assessment, particularly the observational and report-writing pieces, but hands-on device trials are harder to run at a distance.
Little Words' quiz at littlewords.ai/start can help you organize your observations about your child's current communication before your first evaluation appointment, which makes that appointment more efficient and more useful.
Frequently asked questions
At what age can a child have a feature matching AAC assessment?
There is no minimum age. ASHA's position is that AAC evaluation is appropriate for individuals of any age or ability level. In practice, many children receive AAC evaluations in early intervention, meaning before age three, particularly when there are significant communication delays. Earlier trials mean earlier access to communication, which matters for language development.
How long does a feature matching assessment take?
A thorough feature matching assessment, including initial profile, device trials, and report writing, usually takes four to eight weeks from first appointment to final report. The trial phase alone should be at least two to four weeks per system in real-world settings. One-day assessments that skip trials are not considered best practice and produce weaker funding documentation.
Does my child need to be able to speak at all to use AAC?
No. AAC is appropriate for children who are non-speaking as well as those who have some speech but not enough for their communication needs. Children who are minimally verbal or non-verbal are often the clearest candidates. Research also shows AAC does not inhibit speech development; in most studies it supports it. [7]
What is the difference between a low-tech and high-tech AAC system in feature matching?
Low-tech systems include paper-based communication boards, PECS books, and printed core vocabulary boards. They have no electronics, no charging, and no breakage risk. High-tech systems are electronic speech-generating devices, either dedicated hardware or tablet apps. Feature matching evaluates both categories. Some children do best with low-tech permanently; others use low-tech as a backup to high-tech.
Can a school refuse to do a feature matching AAC evaluation?
A school cannot refuse a written request for an assistive technology evaluation if the child is eligible under IDEA and AT may be needed for educational benefit. If the district refuses, they must provide prior written notice explaining why. Parents can then request mediation or a due process hearing. Citing ASHA's no-prerequisite position and IDEA's AT mandate in your written request strengthens your case.
Does insurance cover the cost of an AAC evaluation?
Many private insurance plans cover AAC evaluations when billed as a speech-language pathology evaluation, particularly with a physician referral. Medicaid covers AAC evaluations for children under EPSDT in most states. Medicare has its own SGD coverage criteria for adults. Always get pre-authorization and ask your SLP to document medical necessity clearly in the referral.
What is aided language input, and should it be part of my child's AAC plan?
Aided language input means communication partners use the child's AAC system themselves to model language throughout the day, more than to prompt the child to use it. It's one of the most evidence-backed strategies for building AAC use. [7] Any feature matching report that doesn't include implementation guidance for aided language input is incomplete.
How do I know if the AAC system selected by feature matching is working?
Track three things over time: how many different vocabulary items the child uses independently, how often they initiate communication rather than just respond, and whether they're using the device across multiple settings. Tools like the Communication Matrix (free at communicationmatrix.org) give you a structured way to measure communication growth every few months.
Can feature matching be done for a child who already has a device?
Yes, and it often should be. Children change. If a child received a device two or three years ago without a thorough feature matching process, or if their abilities have changed significantly, a reassessment makes sense. Reassessment is also appropriate when a child's funded device is up for replacement, since insurers often require updated documentation.
What is the role of parents in the feature matching assessment process?
Parents provide information about the child's daily routines, motivations, frustration patterns, environments, and communication partners that no clinical assessment can capture. You should be present for observation sessions, contribute to the communication profile, and participate in training on whichever system is recommended. If an SLP sidelines you during evaluation, that's a red flag.
Is eye gaze technology considered in feature matching, and who is it for?
Eye gaze technology lets a child control a device by tracking where they look, and it's assessed as part of feature matching for any child who lacks reliable hand or head control. It requires good visual acuity and consistent visual field access. Eye gaze systems cost more than touch-access devices and take longer to calibrate, so they're recommended when other access methods genuinely aren't viable.
How does a feature matching assessment differ from a standard speech evaluation?
A standard speech evaluation focuses on articulation, language skills, fluency, and voice. A feature matching assessment for AAC goes further into motor access, sensory profile, symbol understanding, environmental factors, and device trials. It also produces a different output: a device recommendation with funding rationale rather than a speech therapy plan alone. Some SLPs do both in one process; others refer out for the AAC component.
What vocabulary systems are usually considered during feature matching?
The main frameworks are core vocabulary (high-frequency words usable across contexts), fringe vocabulary (topic or person-specific words), activity-based vocabulary, and whole-word or phrase-based systems. Feature matching considers which vocabulary organization fits the child's language level, cognitive profile, and daily communication needs. Most well-built systems combine core vocabulary with customizable fringe pages.
Sources
- ASHA, Augmentative and Alternative Communication: Overview: ASHA defines feature matching as 'the process of comparing an individual's abilities and needs to the characteristics or features of AAC systems and devices.'
- Augmentative and Alternative Communication journal (Taylor & Francis): Research in Augmentative and Alternative Communication documents AAC device abandonment rates, with some studies reporting abandonment in roughly a third of device users.
- ASHA, Scope of Practice in Speech-Language Pathology: ASHA's scope of practice includes AAC evaluation and states that individuals of any age, type, or severity of disability may benefit from AAC with no prerequisite skills required.
- ASHA, State Assistive Technology Programs: ASHA notes state assistive technology programs are federally funded under the Assistive Technology Act and offer device lending at no cost.
- Journal of Autism and Developmental Disorders, Schlosser & Wendt 2008 (no-prerequisites research): Research in JADD found no evidence that symbolic understanding, cognitive ability, or oral language level should be treated as prerequisites for AAC.
- Medicaid.gov, Early and Periodic Screening, Diagnostic and Treatment (EPSDT): Medicaid coverage for children under EPSDT requires coverage of medically necessary assistive technology in most states regardless of cost.
- ASHA, Aided Language Input / Modeling: Aided language input, where partners model language using the AAC system, is one of the most evidence-backed strategies for building AAC use and does not inhibit speech development.
- Communication Matrix, Oregon Health & Science University: The Communication Matrix tracks communication functions across seven levels from pre-intentional to language use and is free online.
- U.S. Department of Education, IDEA Individuals with Disabilities Education Act: Under IDEA, school districts must complete evaluations within 60 days of written parental request, and IDEA mandates assistive technology evaluations for eligible students at no cost to families.
- ASHA, AAC Evidence Maps: ASHA's evidence maps document research support for AAC interventions across populations including autism and childhood motor speech disorders.
- American Academy of Pediatrics, AAC and Communication Supports Policy: AAP supports early identification and referral for communication supports including AAC for children with developmental and communication disorders.