AAC is any device, system or method that improves the ability of a child with communication impairment to communicate effectively. Although AAC is often used to refer to formal communication devices and systems such as sign language, communication boards or voice output communication aids (VOCAs), it can include less sophisticated means of communication such as facial expressions, non-speech vocalizations, idiosyncratic gestures, etc.


AAC is used when a child does not develop communication in the normal fashion, or experiences a significant delay in its development. AAC is not merely a substitute for how the child is currently communicating. It is used to augment that communication, replacing only elements that are unintelligible, socially unacceptable, or harmful to the child or others. Ideally, an AAC system includes more than one mode of communication, with the child using whichever is the most efficient given the persons, setting and activity at hand. Very often one of the modes of communication in an AAC program is natural speech.


Broadly speaking, communication occurs with at least one other person and in the context of the environment, and serves the following functions:

  • To indirectly control the environment, for example to obtain or reject something.
  • To regulate social interactions, for example to express an emotion or to interact with a friend.
  • To receive and convey information and ideas.

Examples of Alternative and Augmentative Communication (AAC)

  • Low-tech systems. Simple paper or object based systems, i.e. do not require a battery.
  • Light-tech systems. Simple voice output devices, which require a battery; although no sophisticated charging mechanism is required.
  • High-tech systems. Sophisticated voice output devices, which require a battery, as well as training and ongoing support.