AAC (Augmentative and Alternative Communication). A means of communication for people who are unable to speak or who have speech that is difficult to understand. AAC systems fall into two main categories: unaided and aided.
Unaided systems make use of the body, for example sign language, key word signing and natural gestures.
Aided communication systems comprise two categories - low technology and high technology. Low technology systems include the use of objects, photographs, picture symbols, letters for spelling and visual timetables. High technology systems include voice activated communication aids (VOCA) and computer based systems.
Acquisition. The phrase "language acquisition" is used to describe the stages of language development in children between the ages of 9 months and 5 years. It can also be used to describe how children with specific learning difficulties, or adults with speech and language disorders, develop their communication skills.
Aphasia, also known as dysphasia. The most common causes of aphasia are cerebrovascular accident (stroke), head injury or brain tumour. When these events occur in the language centres of the brain, both the understanding and use of language is impaired. Both children and adults can be affected.
Apraxia of Speech. Impairment in the ability to program movements of the tongue, lips and throat, required to produce the proper sequence of speech sounds.
Articulation. Structures of the mouth (i.e. lips, teeth, tongue, soft palate) facilitate precise movements to produce different speech sounds.
Comprehension. The process used by humans to understand communication including speech, written language and gesture.
Cognition. The process of thinking.
Developmental delay. Acquisition of language and/or other milestones can occur at a slower rate compared to peers of the same age.
Down Syndrome. A chromosome abnormality (due to an extra copy of the 21st chromosome) that often results in cognitive and other cognitive impairments.
Dysarthria. Difficulty producing speech as a result of damage to those parts of the brain that govern the muscles of articulation, respiration, resonance and voice.
Expressive language. The use of spoken or written words to communicate with others (e.g., speech, writing).
Intellectual disability. Incomplete development of expected cognitive milestones. Children and adults with intellectual disability can have difficulty in learning new skills, including communication skills.
Pragmatics. The rules for the use of language in social context and in conversation (e.g., eye contact, humour, turn taking).