This is an excellent open source software based on the long time research and efforts of the Speech and Accessibility Group of the Department of Informatics and Telcommunications, National and Kapodistrian University of Athens, leaded by Professor Georgios Kouroupetroglou.
This is an overview from the official site of ITHACA open source AAC software.
Overview
Augmentative and Alternative Communication (AAC) attempts to compensate for temporary or permanent impairments, activity limitations, and participation restrictions of individuals with disorders of speech-language production and/or comprehension, including spoken and written modes of communication. ITHACA framework is an Open Source, component-based environment that facilitates software developers and application integrators to build and assemble computer-based interpersonal AAC aids.
