Assistive Technology for Communication Impairments

Approximately 14 million people in America have a speech, voice, or language disorder. Speech and language disorders may result from […]

Approximately 14 million people in America have a speech, voice, or language disorder. Speech and language disorders may result from hearing loss, birth-related conditions, a learning disability, or physical conditions. The disorder may result in stuttering, problems with articulation, voice disorders, or aphasia. Individuals with severe speech and language disorders may be nonspeaking.

One common type of adaptation used by nonverbal and noncomprehensive speakers is an Augmentative and Alternative Communication (AAC) system. This type of assistive technology refers to aids, strategies and techniques designed to enhance a person’s existing communication skills. These AAC systems may be laminated paper consisting of pictures or words, electronic devices capable of adaptive access and voice-to-output, or computer based systems with vocal synthesis. Augmentative and alternative communication systems can be readily adapted to provide for the special needs of the person.

Augmentative and Alternative Communication

AAC refers to any device, system or method that improves the ability of an individual with a communication impairment to communicate effectively. Although AAC is often used to refer to formal communication devices and systems such as sign language, communication boards or voice output communication aids (VOCAs), it can include less sophisticated means of communication such as facial expressions, non-speech vocalizations, idiosyncratic gestures, etc. AAC is used when an individual does not develop communication in the normal fashion, or experiences a significant delay in its development. AAC is not simply a substitute for how the individual is currently communicating. It is used to augment that communication, replacing only elements that are unintelligible, socially unacceptable, or harmful to the individual or others. Ideally, an AAC system includes more than one mode of communication, with the individual using whichever is the most efficient, given the person, setting and activity at hand. Very often one of the modes of communication of an AAC system is natural speech.

AAC Devices

An AAC device refers to a piece of equipment used for communication. Today’s AAC devices offer a range of features that address the variable language requirements of individuals with severe communication impairments. There are three categories of AAC devices that have distinct technological and functional characteristics.

AAC devices with digitized speech output;

AAC devices with synthesized speech output, which require message formulation by spelling;

AAC devices with synthesized speech output, which permit multiple methods of message formulation.

These types of AAC devices employ two principal means of speech production: digitized and synthesized speech. In terms of quality, digitized speech is more natural sounding than synthesized speech because it is a recorded speech. However, both digitized and synthesized devices produce speech that is highly intelligible to the listener. AAC devices with digitized speech are referred to as ‘closed’ systems because the device’s entire capacity for speech output is limited to the words, phrases, or messages that have been pre-stored for the user. Synthesized speech devices are ‘open’ systems because users independently can construct original messages.

Letter-based AAC Systems

Letter-based communication systems can provide a reliable means of communication for persons with severe speech disorders. The systems, also known as spelling-based systems, are divided into two categories – low-tech manual boards and speech-generating keyboard devices. The manual board is a piece of paper or other material with the alphabet written on it in squares, whereas a speech-generating keyboard is an electronic device that will speak the words typed on it. With the manual board, the person points to printed alphabet letters and with the speech-generating keyboard, the person manipulates a keyboard to enter information.

To assist with speed of communication, high-tech solutions may include features such as grammar prediction, word prediction, increasing/decreasing the length of the prediction list, flexible abbreviation, macros, automatic spacing and capitalization, and modified keyboard layouts. Designed to reduce the number of key strokes involved in composing a message, such strategies generally are believed to serve that purpose. Research demonstrated that the number of key strokes can be reduced by 35–50% when using strategies such as word prediction.


ETRAN is a system designed to help individuals with speech disorders such as dyspraxia communicate. The system is an acronym for the five most frequently used letters in the English language. ETRAN is a 24×18 inch plexiglass board with the center cut out. Letters are placed around the frame and the user chooses the desired letter by looking at it. The user and the “listener” sit opposite to each other. The listener watches the user’s eye movements through the hollow center of the board. The user selects a letter by first looking at a group of letters and then by looking at one of the four corners of the board. The person that is communicating with the user indicates the letter verbally until the word is formed. At that point, the user will look into the middle of the board to indicate the end of a word. Many times, the receiver will guess the word prior to completion.

Speech Enhancement

Speech enhancement is used by people who prefer to rely on verbalization yet are hard to understand. Speech enhancement devices are worn around the head with a microphone. Through electronics, the device attempts to clarify the speech. The speech may be altered and/or increased in volume. It has been tested with a variety of disability voice styles such as cerebral palsy, Parkinson’s, muscular dystrophy, multiple sclerosis, Lou Gehrig’s disease, and paralyzed vocal cords. In the majority of cases, there is substantial improvement.

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