“In some cases these individuals lack all spoken language: their vocalizations only include atypical non-speech sounds and some vowel approximations. In other cases, their expressive language is extremely limited with just a few words or fixed phrases (e.g., Want X) used infrequently and only in limited contexts. Other children included in this group may have some spoken language, but they are primarily echolalic or use stereotyped or scripted language in ways that appear non-communicative.”
For these children, it is especially important that language skills be built to decrease frustration and tantrums and increase ability to navigate and communicate with their community. When considering language development, it is also important to consider whether your child can communicate their emotional state, an event that happened earlier, or use specific language to communicate pain with you and their medical team.
Based on decades of research and clinical development, it has been determined that AAC does NOT negatively impact speech development, but often increases it. In a 2006 study, 94% of participants (ages 2 to 60) across multiple studies demonstrated an increase in speech development and verbal language.
While it’s great to know that verbal language/speech development will not be negatively impacted by utilizing AAC, it is also important to remember that AAC is used to increase language skills and communicative competence (grammatical knowledge and social knowledge as to how to use language). AAC may allow individuals to skip the motor and cognitive demands of speech production and focus on building communication and language skills. Once basic communication and language skills are established, they may have better speech production outcomes with speech therapy.
If your SLP recommends AAC, it's not because they believe your child may never talk/use verbal language to communicate. By recommending AAC, the hope is always to build language skills to later develop verbal language. AAC is never the last resort to improve communication skills but is often an amazing tool to develop speech and language!
“Minimally verbal school-aged children with autism spectrum disorder: the neglected end of the spectrum.” by Helen Tager-Flusberg and Connie Kasari in Autism Research: Official Journal of the International Society for Autism Research, December 2013 vol. 6,6, 468-78. doi:10.1002/aur.1329
"Effects of Augmentative and Alternative Communication Intervention on Speech Production in Children With Autism: A Systematic Review" by Ralf W. Schlosser and Oliver Wendt in American Journal of Speech-Language Pathology, August 2008, Vol. 17, 212-230. doi:10.1044/1058-0360(2008/021)
"The Impact of Augmentative and Alternative Communication Intervention on the Speech Production of Individuals With Developmental Disabilities: A Research Review" by Diane C. Millar, Janice C. Light and Ralf W. Schlosser in Journal of Speech, Language, and Hearing Research, April 2006, Vol. 49, 248-264. doi:10.1044/1092-4388(2006/021)