AAC means all of the ways that someone communicates besides talking. People of all ages can use AAC if they have trouble with speech or language skills. Augmentative means to add to someone’s speech. Alternative means to be used instead of speech. Some people use AAC throughout their life. Others may use AAC only for a short time, like when they have surgery and can’t talk.
https://www.asha.org/public/speech/disorders/aac/