This term used to describe methods of communication which can add to the more usual methods of speech and writing when these are impaired. AAC includes unaided systems of communication such as signing (for example, Makaton) and gesture, as well as aided techniques. These aided techniques range from the use of low technology such as picture or symbol charts to the most sophisticated computer technology currently available. A well‐known user of a sophisticated high technology device is the scientist Stephen Hawking. AAC can be a way to help someone understand what is being communicated to them, as well as a means of expression. See also picture exchange communication system.
http://www.communicationmatters.org.uk Provides a wealth of information about AAC including details of suppliers, publications, assessment centres, and online forums.