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Feature-Matching in AAC Assessment: Voice Features

Updated: Jun 6, 2023

Feature-matching in AAC assessment is an important component when identifying the most effective and efficient AAC system for AAC users.

  • Originally defined by Shane & Costello (1994), feature matching is a systematic process in which an AAC user’s strengths and needs are matched to available AAC tools and strategies. This includes both current and future needs (Gosnell et al., 2011).

  • Through the feature-matching process, speech-language pathologists make clinical decisions related to an AAC user's AAC system based on many different areas including the AAC user's speech, language, motor, and cognitive abilities as well as social, cultural, and educational domains.

One of the important features to consider during this process is voice features. There are many different types of voice features to choose from! This depends on the AAC device, language system, and/or AAC app.

  • This is an important feature when selecting an AAC system for an AAC user as it represents the user’s unique voice (Marx & Locast, 2016). This feature allows a user to be heard and understood by others!

The AAC assessment process can be overwhelming for both clinicians and the AAC user. There are many decisions to be made related to recommending an AAC system and choosing an appropriate voice can sometimes be an afterthought. However, this is an important feature to consider during the assessment process!

  • Most AAC systems offer speech output using digitized speech and synthesized speech, or a combination of both (Drager et al., 2010). Synthesized speech is electronically produced while digitized speech utilizes natural speech that has been recorded, stored, and reproduced (ASHA, n.d.).

Through the different AAC apps and language systems, there are many decisions related to the voice output.

  • Personalization Options: There are ways to personalize the voice for the user such as decisions related to gender, age, pitch, and rate (Marx & Locast, 2016). Some apps offer voice by age such as a child, adolescent, or adult voices. Often you can find the voices broken down by age in the settings of the app or when setting up a user profile you can select a voice and later change it through the settings.

  • Language Options: Several of the AAC apps available provide several different language options. If the app doesn't have the user's specific language, there are often options for downloading additional language. Some apps offer free voices as well as the option to purchase a "premium" voice. With a Forbes AAC device it's easy to choose an upgraded voice by just noting it in the order/quote form so it can be downloaded before being shipped to the user!

  • Speaker Type: Another consideration is the type of speaker an AAC device offers. With our WinSlate and ProSlate devices, the user will receive a SoundPOD™, the world's first wearable speaker module. This a reason many users choose a Forbes AAC device as they will then receive the SoundPOD which can be worn on a neck lanyard allowing the AAC user's voice to come directly from the person, rather than from the back or side of the device. It promotes NATURAL communication! Additionally, the SoundPOD provides loud audio output to make a user's voice heard in any situation while maintaining clarity at all volume levels , easily connects wirelessly through Bluetooth technology, and has a high capacity lithium ion battery, so it can be used without draining power from the device.

Feature-matching is an important component in the AAC assessment process. When selecting the voice features for an AAC user, consider the type of voice (synthesized or digitized), consider the many different personalization options (e.g., gender, age, rate, pitch), and choose the appropriate language for the user (Marx & Locast, 2016).


  • American Speech-Language-Hearing Association (n.d.). Augmentative and Alternative Communication (Practice Portal).

  • Beukelman, D. R., & Light, J. C. (2020). Augmentative & alternative communication: Supporting children and adults with complex communication needs (5th ed.). Brookes.

  • Drager, K. D., Reichle, J., & Pinkoski, C. (2010). Synthesized speech output and children: A scoping review. American Journal of Speech-Language Pathology, 19(3), 259–273.

  • Gosnell, J., Costello, J., & Shane, H. (2011). Using a clinical approach to answer “what communication apps should we use?” SIG 12 Perspectives on Augmentative and Alternative Communication, 20(3), 87–96.

  • Locast, M. & Marx, A. (2016). AAC Feature Matching Overview [Presented at The American Academy for Cerebral Palsy and Developmental Medicine AACPDM) Annual Meeting]. Accessed from: (June 8th, 2022).

  • Shane, H., & Costello, J. (1994, November). Augmentative communication assessment and the feature matching process. Mini-seminar presented at the annual convention of the American Speech-Language-Hearing Association. New Orleans, LA.

  • Vanderheiden, G. C., & Yoder, D. E. (1986). Overview. In S. W. Blackstone (Ed.), Augmentative communication: An introduction (pp. 1–28). Rockville, MD: American Speech Language-Hearing Association.

Katie Threlkeld, M.S., CCC-SLP is a licensed, ASHA-certified speech-language pathologist and the Educational Program Developer at Forbes AAC. She has over eight years of experience in AT and AAC assessment and treatment with both the pediatric and adult populations. Katie has presented at the state and national level on AAC topics and she has University teaching experience at the undergraduate and graduate level.

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