Basic augmentative and alternative communication (AAC) device characteristics are described below. To learn more about AAC, see the Augmentative Communication (AAC) technology review.
A variety of strategies may be used to access a communication device. Most commonly, individuals use direct selection, by typing on a keyboard or pointing to images on a touch screen. Individuals with motor impairments may use a joystick, mouse, head mouse, or switch to select desired items. Many different types of switches are commercially available to allow access with nearly any controlled motor movement. Switch users access an AAC device by scanning through the available vocabulary, and pressing the switch when the desired item is highlighted.
Recently, eye gaze communication has become effective and commercially available on a number of high-tech communication systems. A camera continuously monitors the position of the user’s eyes, allowing individuals with severe motor impairments to select an item on the communication display by looking at it for a specified period of time. This technology, though expensive, can greatly speed communication for those with severe physical impairments.
Vocabulary may be represented with photographs, picture symbols, or letters. Several picture symbol sets are widely used for augmentative communication, including Mayer Johnson PCS symbols, Minspeak symbols, and Symbol Stix. Children with the potential for literacy should also be provided with access to spelling within their AAC system.
Vocabulary may be arranged in various ways on the AAC system, in order to match the child’s abilities and preferences. Some systems place the most common words in English (core words) in a static position on the display, while less frequently used words change depending on the user’s selection. Other systems are based on pages of vocabulary arranged by category. Some systems require the user to recall sequences of symbols. Other systems require the user to scan pages of vocabulary to locate the target word. Visual scene displays are also used to organize vocabulary. With a visual scene display vocabulary is located under specific portions of a photograph from the user’s environment. For example, the child might select the faucet in the kitchen to request a drink of water.
Selection of vocabulary for a communication system is critically important for the development of a child’s language abilities. Vocabulary should include all parts of speech, rather than just nouns. Children should be provided with the opportunity to learn to combine words into sentences. Vocabulary must be personalized and continuously adapted to the child’s needs.
The system may provide voice output with either digitized or synthesized speech. Digitized speech is prerecorded human speech. Synthesized speech is computer generated. A number of good quality synthesized voices are now available for high-tech systems. Children need a gender appropriate child’s voice in their AAC system.
Augmentative communication systems are available in various sizes from large systems, which must be attached to a wheelchair mount, to small devices, which fit in a pocket. Considerations for size include the user’s motor skills, vision, vocabulary needs, and communication environment. Small portable devices are preferred for ambulatory users. Larger devices are needed for eye gaze access.
Augmentative communication systems can be divided into two basic types of equipment. “Dedicated” devices are manufactured for the primary purpose of providing communication for those who cannot speak intelligibly. A number of manufacturers specialize in augmentative communication equipment, such as Dynavox, Prentke Romich Company, Tobii ATI, and Saltillo. Most AAC manufacturers provide free training, 24 hour customer support, device loan programs, funding assistance, and a manufacturer’s representative to assist consumers. Dedicated devices are manufactured for sturdiness and reliablility. Many of the more costly devices are based on fully functional computers and allow alternative access to telephone, email, and internet.
“Non-dedicated” augmentative communication devices are composed of mainstream electronic devices such as a smart phone, iPad, or notebook computer, to which AAC software or applications have been added. A revolution has occurred in the augmentative communication industry since the widespread introduction of tablet computers, such as the iPad. A number of AAC applications have been developed for tablet computers. These applications, such as Proloquo2Go, and Touch Chat, have received widespread media attention. Many parents are drawn to this technology due to relatively low cost, easy availability, and the attractiveness of the devices. Some children are more willing to use a mainstream device than a specialized communication system. Drawbacks to use of these non-dedicated systems include lack of insurance funding, limited customer support and training, device fragility, and very limited access methods. Several companies, such as Origin Instruments and Ablenet, are developing commercially available switch access for the iPad, but options for alternative access are quite limited at this time. Providers and families should also be aware that not all AAC applications are complete or appropriate. Both Proloquo2Go and Touch Chat provide access to complete symbol vocabularies which include all parts of speech. Other less expensive applications are often just collections of photographs. In any case, an evaluation with a speech/language pathologist is needed prior to purchase, so that the communication needs of the child are fully addressed.
|Author:||Laura Barnett, MCSD/CCC - 2/2014|