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Augmentative and alternative communication

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Augmentative and alternative communication (AAC) refers "to an area of research, clinical, and educational practice. AAC involves attempts to study and when necessary compensate for temporary or permanent impairments, activity limitations, and participation restrictions of individuals with severe disorders of speech-language production and/or comprehension, including spoken and written modes of communication".[1]



Aided and Unaided AAC

AAC is used by individuals with severe communication disorders for whom gestures, speech, and/or writing is temporarily or permanently inadequate to meet all of their communication needs. Speech may be replaced or augmented by using a variety of modes:

Aided AAC

An AAC aid is any "device, either electronic or non-electronic, that is used to transmit or receive messages".[2] The skills, areas of difficulty and communication requirements vary greatly within the AAC user community, and so an equally diverse range of communication aids exists to meet these demands.

Low Tech

Low-tech aids are devices which do not need batteries or electricity to meet the user's communication needs.[3] These are often very simple devices created by placing phrases letters, pictures or symbols on a board or in a book. Depending on their physical abilities and limitations, the user then accesses the device by pointing to the appropriate message with their fingers, a non-electronic pointer, or eye gaze.[3]

Low-tech aids are limited in terms of the amount of messages a single device can convey: Only so many messages can fit on a single low-tech communication board or communication book. In comparison, natural speech can convey infinite messages, and high-tech aids are only limited in terms of their memory store and battery life.

High Tech

High-tech AAC aids are electronic devices that permit the user to communicate with others by producing digitized or synthesized speech or by typing out messages.[3][4] These devices can also be referred to as Speech Generating Devices (SGDs) or Voice Output Communication Aids (VOCAs).[3] A diverse array of such electronic devices is presently available and each user is matched with the device that is most suitable for their needs and skills. Some devices can be simple electronic communication boards that produce the word, phrase or a story stored under chosen symbols. Other devices can say the words or the letters that are typed by the user.[3] The more sophisticated electronic AAC devices consist of communication software installed on fully functional computers which are adapted to the users' physical capabilities. The users can then switch from the communication program to general operating system and use their device to access internet, email, games, word processors and other standard computer software.

These devices vary in price, size, and amount of information they can store. In terms of portability, some devices are easy to carry around while others can be mounted to a wheelchair if necessary. There is usually more than one way to operate the devices, depending on the physical capabilities of the user. They can be operated using touch screens, switches, joysticks, mouth-operated mouses or programs which track the eye gaze of the user.[4]

Continuous advancement and new development of high-tech communication devices is highly important for improving the communication abilities of people who do not use natural speech. It is important to keep in mind that electronic devices operate on batteries which need to be frequently changed or charged. Moreover, in the event that a device stops working, the user should have access to a low-tech device until the electronic one is fixed.[3]

Unaided AAC

Unaided AAC includes sign language and gesture systems, as well as body language.

Symbols

Some people who use AAC can read and spell; others cannot, and need communication aids on which language elements are represented by pictures or graphic symbols such as Picture Exchange Communication System (PECS) or Blissymbols.

Access

Traditional communication is accessed through the mouth (by speaking), the ears (by hearing), the eyes (by seeing) and the brain (by appropriately processing meaning). People with impairments to any of these organs may require augmented or alternative access to communication.

Some people with severe communication impairments can use their hands; others cannot, and have to use alternatives, such as mouth sticks, headsticks, switches or eye-pointing.

  • Direct Selection: An individual points to the desired symbol using a finger or alternative selection technique (i.e., headpointer or eyegaze pointing).
  • Scanning: An individual is offered an array of symbols. As the communication system or partner scans through the symbols, the AAC user indicates his/her desired choice by using the alternative selection technique (i.e., pointing, switch access, head nodding) to select the desired symbol.

Rate enhancement strategies

Rate enhancement strategies increase the rate of communication output of the user and as a result enhance the efficiency of communication. There are two main options for increasing the rate of communication for AAC devices: Encoding and prediction.[5]

  • Encoding is the way a user is able to produce messages using the device. If an entire word, phrase or sentence can be retrieved with a one or two symbol or letter code, communication will occur faster.[5]
  • Iconic Encoding uses pictures, line drawings, or shapes to represent frequently used concepts. This is especially useful for non-literate users, as it gives them access to large vocabularies while requiring fewer keystrokes and minimal spelling or reading abilities. For example, a picture of a toilet may represent “I need to use the bathroom.”[6]
  • Semantic Compaction (Minspeak) uses icons with multiple meanings which are sequenced together. The meaning of the message is then dependent upon each icon in a particular sequence. For example, typing “food + yellow + B” may represent “banana”.[6][7]
  • Letter Encoding/Abbreviation-Expansion stores words, phrases or sentences as abbreviations, which eliminates having to type complete words or phrases. For example, typing “HH” may represent the greeting, “Hello, how are you?”.[7]
  • Alpha-numeric/Numeric Encoding stores messages under combinations of letters and/or numbers. For example, typing “G1” may represent "Greeting 1", producing "Hello, how are you?”.[6]
  • Prediction refers to the ability of the device to guess the word that is being typed by the user and to provide choices in message output. When the guess is correct, the user selects it and no longer has to type the entire word. The user is also provided with additional choices to select in case the initial guess is incorrect. The device determines the possible choices offered based on frequency in language, word association, past choices, or grammatical suitability.[5][7]
  • Word Completion allows the device to predict the end of a word based on the first letters typed and a menu of likely words is offered based on the user’s initial keystrokes. If the desired word is offered, the user can select it without the need to continue typing the rest of the word. For example, if the user types “h-e”, “hello" or "help” may be offered as choices to complete the word.[6][7][5]
  • Next Word Prediction allows the device to predict words based on word pairings and/or grammatical rules of the words occurring before it. For example, if the user types, “I am”, the device may offer typical responses to this sequence of words such as “going", "feeling".[5]
  • Linguistic Prediction lets the device offer words that agree in tense, case and number based on previous words in the message. For example, if the user has typed “tomorrow”, only words in the future tense will be offered as choices.[5]

Team

Assessments for individuals with AAC needs may be undertaken by a communication consultancy team who may consist of a speech and language therapy professional, an occupational therapist and/or a clinical scientist.

Visual impairment

A group of users who can benefit from AAC are the blind and visually impaired. Whenever possible, AAC devices should be designed for Dynamic Diversity [8], where the interface is accessible not only to “typical” AAC users, but also to minority populations who need to use the device. Luckily, we have the means to manipulate both high and low tech AAC devices in order to make them accessible to blind AAC users. For individuals with some residual vision, it is beneficial to have an AAC device with modified visual output. This may include large print and/or clear, simple graphics [9]. Tactile symbols can be used with blind AAC user. Tactile symbols are textured objects, real objects or parts of real objects [10]. These tangible symbols are considered meaningful to the AAC user and thus allow them access to language. They can be used on low or high tech displays and also on switches. Of course, having a tangible symbol may decrease the number of symbols available to the AAC user at one time. Braille, is an example of a tactile reading and writing system. Auditory symbols are also useful for blind AAC users. Morse Code is an example of an auditory symbol system. Dots and dashes represent letters, words, and phrases. There are some AAC devices that can convert Morse code into text or speech. Another auditory symbol is speech. Devices that offer auditory scanning can be helpful to blind AAC users as they allow the user to scan through options via an alternate modality (hearing as opposed to vision)[11].


Terminology Used in AAC

Symbol: Something used to represent another thing or concept. For example, a picture or line drawing of a dog to represent dog.

Symbol Set: A set of symbol that is closed in nature; symbol set can be expanded, but it does not have clearly defined rules for expansion (e.g., Picture communication symbols).

Symbol System: A set of symbol; includes rules or a logic for the development of symbols (e.g., Blissymbols).

Speech Generating Device: An electronic assistive device that produces speech (e.g., Dynavox, Mercury).

VOCA: Voice Output Communication Aid; other term for electronic assistive device producing speech

Assistive Communication Device: Electronic or non-electronic assistive technology device that provides external assistance for communication.

AAC System: An integrated network of symbols, techniques, aids, strategies, and skills.

Input Method: Technique used to select representations of the wanted utterances from an electronic device (e.g., touchscreen selection, eyegaze pointing, switch access)

Tangible Symbols: Tangible symbols are objects or pictures that are used as symbols by individuals who are not able to communicate using more conventional symbol systems. Tangible symbols bear an obvious and concrete relationship to the visual or tactile properties of the entities that they represent. They are a type of “augmentative and alternative communication” (AAC).

See also: Blissymbolics

References

  1. ^ "Roles and Responsibilities of Speech-Language Pathologists With Respect to Augmentative and Alternative Communication: Position Statement". www.asha.org. 2005. Retrieved 2009-01-23.
  2. ^ Beukelman, D.R., and Mirenda, P: Augmentative & Alternative Communication, page 4. Paul H Brookes Publishing Co., 2005
  3. ^ a b c d e f Technology. International Society for Augmentative and Alternative Communication. Retrieved on March 19 2009.
  4. ^ a b Connections. Learning Independence through Computers Inc. Retrieved on March 20 2009.
  5. ^ a b c d e f Rate Enhancement. Augmentative and Alternative Communication at the University of Washington, Seattle. Retrieved on March 19 2009.
  6. ^ a b c d Venkatagiri, H. (1995). "Techniques for Enhancing Communication Productivity in AAC: A Review of Research". American Journal of Speech-Language Pathology, 4:36-45
  7. ^ a b c d Types of AAC Devices. Augmentative Communication, Incorporated. Retrieved on March 19 2009.
  8. ^ Gregor, P., Newell, A.F., Zajicek, M. (2002). Designing for Dynamic Diversity – interfaces for older people. Proceedings of the fifth international ACM conference on Assistive technologies. Edinburgh, Scotland. Session: Solutions for aging. Pages 151-156.
  9. ^ Gregor, P., Newell, A.F., Zajicek, M. (2002). Designing for Dynamic Diversity – interfaces for older people. Proceedings of the fifth international ACM conference on Assistive technologies. Edinburgh, Scotland. Session: Solutions for aging. Pages 151-156.
  10. ^ Beukelman, D., Mirenda, P., Franklin, K. & Newman, K. (1992). Persons with visual and dual sensory impairments. In D. Beukelman & P. Mirenda, Augmentative and alternative communication: Management of severe communication disorders in children and adults. Baltimore: Brookes, 291-309.
  11. ^ Beukelman, D., Mirenda, P., Franklin, K. & Newman, K. (1992). Persons with visual and dual sensory impairments. In D. Beukelman & P. Mirenda, Augmentative and alternative communication: Management of severe communication disorders in children and adults. Baltimore: Brookes, 291-309.

Works Cited

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