Augmentative and alternative communication
Augmentative and alternative communication encompasses the communication methods used to supplement or replace speech or writing for those with impairments in the production or comprehension of spoken or written language. AAC is used by those with a wide range of speech and language impairments, including developmental disabilities such as cerebral palsy, intellectual disability and autism, and acquired conditions such as amyotrophic lateral sclerosis and Parkinson's disease. AAC can be a permanent addition to a person's communication or a temporary aid. Stephen Hawking, probably the best-known user of AAC, had amyotrophic lateral sclerosis, and communicated through a speech-generating device.
Modern use of AAC began in the 1950s with systems for those who had lost the ability to speak following surgical procedures. During the 1960s and 1970s, spurred by an increasing commitment in the West towards the inclusion of disabled individuals in mainstream society and emphasis on them developing the skills required for independence, the use of manual sign language and then graphic symbol communication grew greatly. It was not until the 1980s that AAC began to emerge as a field in its own right. Rapid progress in technology, including microcomputers and speech synthesis, paved the way for communication devices with speech output, and multiple options for access to communication for those with physical disabilities.
AAC systems are diverse: unaided communication uses no equipment and includes signing and body language, while aided approaches use external tools. Aided communication methods can range from paper and pencil to communication books or boards to speech generating devices or devices producing written output. The elements of communication used in AAC include gestures, photographs, pictures, line drawings, letters and words, which can be used alone or in combination. Body parts, pointers, adapted computer mice, or eye tracking can be used to select target symbols directly, and switch access scanning is often used for indirect selection. Message generation through AAC is generally much slower than spoken communication, and as a result rate enhancement techniques have been developed to reduce the number of selections required. These techniques include prediction, in which the user is offered guesses of the word/phrase being composed, and encoding, in which longer messages are retrieved using a prestored code.
The evaluation of a user's abilities and requirements for AAC will include the individual's motor, visual, cognitive, language and communication strengths and weaknesses. The evaluation requires the input of family members, particularly for early intervention. Respecting ethnicity and family beliefs are key to a family-centered and ethnically competent approach. Studies show that AAC use does not impede the development of speech, and may result in a modest increase in speech production. Users who have grown up with AAC report satisfying relationships and life activities; however, they may have poor literacy and are unlikely to be employed.
While most AAC techniques controlled by the user are reliable, two techniques have arisen which falsely claim to allow people with intellectual disabilities to communicate. These techniques involve an assistant guiding a disabled person to type on a keyboard or point at a letter board. It has been shown that the facilitator, rather than the disabled person, is the source of the messages generated in this way. There have been a large number of false allegations of sexual abuse made through facilitated communication.
The Convention on the Rights of Persons with Disabilities defines augmentative and alternative communication as forms of communication including languages as well as display of text, large-print, tactile communication, plain language, accessible multimedia and accessible information and communications technology.
The field was originally called "Augmentative Communication"; the term served to indicate that such communication systems were to supplement natural speech rather than to replace it. The addition of "alternative" followed later, when it became clear that for some individuals non-speech systems were their only means of communication. AAC communicators typically use a variety of aided and unaided communication strategies depending on the communication partners and the context. There were three, relatively independent, research areas in the 1960s and 1970s that lead to the field of augmentative and alternative communication. First was the work on early electromechanical communication and writing systems. The second was the development of communication and language boards, and lastly there was the research on ordinary child language development.
Scope
Augmentative and alternative communication is used by individuals to compensate for severe speech-language impairments in the expression or comprehension of spoken or written language. People making use of AAC include individuals with a variety of congenital conditions such as cerebral palsy, autism, intellectual disability, and acquired conditions such as amyotrophic lateral sclerosis, traumatic brain injury and aphasia. Prevalence data vary depending on the country and age/disabilities surveyed, but typically between 0.1 and 1.5% of the population are considered to have such severe speech-language impairments that they have difficulty making themselves understood, and thus could benefit from AAC. An estimated 0.05% of children and young people require high technology AAC. The bulky dedicated devices of the 1970s have evolved immensely while growing the ACC app industry. However, the continued high rates of limited use and abandonment highlight the need for a shift in design, while focusing on minimizing cognitive load and adapting to each user's unique language needs a long with their physical needs as well. Well-known AAC users include physicist Stephen Hawking, broadcaster Roger Ebert and poet Christopher Nolan. Award-winning films such as My Left Foot and The Diving Bell and the Butterfly, based on books by AAC users Christy Brown and Jean-Dominique Bauby respectively, have brought the lives of those who use AAC to a wider audience.Forms of AAC
Unaided AAC
Unaided AAC systems are those that do not require an external tool, and include facial expression, vocalizations, gestures, and sign languages and systems. Informal vocalizations and gestures such as body language and facial expressions are part of natural communication, and such signals may be used by those with profound disabilities. More formalized gestural codes exist that lack a base in a naturally occurring language. For example, the Amer-Ind code is based on Plains Indian Sign Language, and has been used with children with severe-profound disabilities, and adults with a variety of diagnoses including dementia, aphasia and dysarthria. The benefits of gestures and pantomime are that they are always available to the user, usually understood by an educated listener, and are efficient means of communicating.In contrast, sign languages have a linguistic base and permit the expression of an unlimited number of messages. Approaches to signing can be divided into two major categories, those that encode an existing language, and those that are languages in their own right. In the United States of America, Signing Exact English may be considered the most widely used example of the former and American Sign Language as a common example of the latter. Signing is used alone or in conjunction with speech to support communication with individuals with a variety of disorders. The specific hand shapes and movements of sign and gesture require an individual to have adequate fine motor and motor planning skills. Sign languages require more fine-motor coordination and are less transparent in meaning than gestural codes such as Amer-Ind; the latter limits the number of people able to understand the person's communication without training.
Aided AAC
An AAC aid is any "device, either electronic or non-electronic, that is used to transmit or receive messages"; such aids range from communication books to speech generating devices. Since the skills, areas of difficulty and communication needs of AAC users vary greatly, an equally diverse range of communication aids and devices is required.Low-tech
Low-tech communication aids are defined as those that do not need batteries, electricity or electronics. These are often very simple communication boards or books, from which the user selects letters, words, phrases, pictures, and/or symbols to communicate a message. Depending on physical abilities and limitations, users may indicate the appropriate message with a body part, light pointer, eye-gaze direction, or a head/mouth stick. Alternatively, they may indicate yes or no while a listener scans through possible options.Picture Communication Exchange System is a commonly used low-tech communication system that teach individuals how to request, comment, and answer questions.
High-tech
High-tech AAC aids permit the storage and retrieval of electronic messages, with most allowing the user to communicate using speech output. Such devices are known as speech generating devices or voice output communication aids. A device's speech output may be digitized and/or synthesized: digitized systems play recorded words or phrases and are generally more intelligible while synthesized speech uses text-to-speech software that can be harder to understand but that permits the user to spell words and speak novel messages.High-tech systems may be dedicated devices developed solely for AAC, or non-dedicated devices that run additional software to function as AAC devices. These options are typically more affordable than a dedicated device. Examples of AAC applications that function on non-dedicated hardware include Avaz and Spoken. The freedom to use existing, personal devices like smartphones for AAC has resulted in more users.
High-tech AAC may be static or dynamic in form. Static communication devices have symbols in a fixed positions on paper overlays, which are changed manually. To increase the vocabulary available, some static devices have multiple levels, with different words appearing on different levels. On dynamic AAC devices, the user can change the symbols available using page links to navigate to appropriate pages of vocabulary and messages.
High-tech devices vary in the amount of information that they can store, as well as their size, weight and thus their portability. Access methods depend on the abilities of the user, and may include the use of direct selection of symbols on the screen or keyboard with a body part, pointer, adapted computer mice or joysticks, or indirect selection using switches and scanning. Devices with voice output offer their user the advantage of more communicative power, including the ability to initiate conversation with communication partners who are at a distance. However, they typically require programming, and can be unreliable.
High-tech systems can also include keyboard-based solutions that do not require programming with a mix of flexibility, simplicity, and associated reliability. In this case, a keyboard and audio speaker are configured to be create a "talking keyboard" where typed text is spoken directly in an audio speaker. This allows any phrase to be spoken as it is typed using unlimited vocabulary text-to-speech conversion. One simple benefit is that a talking keyboard, when used with a standard telephone or speakerphone can enable a voice impaired individual to have a two-way conversation over a telephone. Game accessibility often utilizes high-tech solutions to allow individuals with disabilities to participate in conversations and use "call outs".
In all cases of use, low tech systems are often recommended as a backup in case of device failure.