Technological Aids for Cerebral Palsy: Augmentative and Alternative Communication (AAC)

Augmentative and Alternative Communication (AAC) is a blanket term that includes all forms of communication except “standard speech.” These forms of communication can include nonverbal cues, gestures, pictures and writing. Augmentative and Alternative Communication can be used to supplement or replace speech for individuals who cannot necessarily communicate verbally.

Individuals with cerebral palsy can have involvement of the face and upper airways, which can sometimes make speech difficult. AAC tools allow children with cerebral palsy to communicate more effectively.

People use an unaided AAC system when they are relying on their body to communicate. This can take the form of sign language, body language or gestures.

People use an aided AAC system (sometimes called an assistive communication device) when they are using their body along with additional equipment or tools. This could take the form of pencil and paper, speech-generating devices (SGDs) or electronic communication aids that allow the user to select images, symbols, letters or words to make a message.

The kind of assistive device or system most appropriate for a person with a disability in verbal expression is entirely dependent on that individual’s strengths and weaknesses. The considerations that have to be taken into account include motor, visual, cognitive, language and communication skills. Individuals who use Augmentative and Alternative Communication systems have varying skills, areas of difficulty and communication needs, so it is important to select the system that is most appropriate for that individual.

Assistive communication devices can be subdivided into a number of types, including adapted writing tools, speech-generating computers, smartphone and touchscreen applications, eye-tracking devices and electronic Braille systems and communication boards. Hearing aids and personal emergency response systems also fall under this category.

With the advent of near-ubiquitous smartphone and tablet usage, the availability of AAC tools has become vastly greater. Indeed, there are entire websites devoted to cataloging available applications for consumer devices such as the iPad, including AppsforAAC.

People use an unaided AAC system when they are relying on their body to communicate. This can take the form of sign language, body language or gestures.

People use an aided AAC system (sometimes called an assistive communication device) when they are using their body along with additional equipment or tools. This could take the form of pencil and paper, speech-generating devices (SGDs) or electronic communication aids that allow the user to select images, symbols, letters or words to make a message.

The kind of assistive device or system most appropriate for a person with a disability in verbal expression is entirely dependent on that individual’s strengths and weaknesses. The considerations that have to be taken into account include motor, visual, cognitive, language and communication skills. Individuals who use Augmentative and Alternative Communication systems have varying skills, areas of difficulty and communication needs, so it is important to select the system that is most appropriate for that individual.

Assistive communication devices can be subdivided into a number of types, including adapted writing tools, speech-generating computers, smartphone and touchscreen applications, eye-tracking devices and electronic Braille systems and communication boards. Hearing aids and personal emergency response systems also fall under this category.

With the advent of near-ubiquitous smartphone and tablet usage, the availability of AAC tools has become vastly greater. Indeed, there are entire websites devoted to cataloging available applications for consumer devices such as the iPad, including AppsforAAC.

Low-tech tools are, by definition, devices that do not need batteries, electricity or the use of electronics. These assisted communication devices often include communication boards or books that contain images, letters, words, phrases or symbols. The user can indicate a particular symbol using a body part, pointer, gaze direction, or a head/mouth stick. A listener can also scan through possible options and the user can indicate yes or no.

High-tech communication aids are a similarly broad category. Generally, these devices allow the device to store and retrieve electronic messages and allow the user to communicate using a speech output function. Devices with speech functions are known as either speech generating devices (SGDs) or voice output communication aids (VOCA). Such devices can be dedicated specifically to AAC functions, or can be integrated into non-specific devices (like a laptop computer or a tablet) to allow those devices to run as an AAC tool.

When it comes to speech output, there are some tradeoffs in AAC technology. Digitized systems use pre-recorded words and phrases, making the output more intelligible, but synthesized speech (while less intelligible) allows the user to speak novel messages. High-tech systems also vary in portability, so a low-tech backup method should always be available. Devices with voice output provide more communicative power but require programming, which can make them unreliable.

AAC can be slower than speech in most cases. Current rate enhancement strategies can speed up the rate of communication using encoding (where abbreviations are used and then expanded into full phrases), or prediction (where the system attempts to predict the message the user is attempting to output).

The spread of smartphones, tablets and other lightweight and portable devices has facilitated the spread of numerous applications specifically designed for helping those with difficulty verbalizing to communicate. This increase allows family members and caregivers to find low-cost, effective communication aids. Eye tracking devices such as the Tobii and mobile apps provide methods for facilitating communication.

There are numerous organizations and websites devoted to the use, development and dissemination of AAC tools, devices and methods. We are providing a brief list of these organizations for reference:

• The AAC Institute is a non-profit organization that works to advocate for those who use AAC technology.
• The International Society for Augmentative and Alternative Communication (ISAAC) hosts conferences and develops publications devoted to AAC.
• The Rehabilitation Engineering and Assistive Technology Society of North American (RESNA) and the National Coalition for Assistive and Rehab Technology (NCART) host a joint scientific conference dedicated to developing technologically advanced communication aids and assistive/rehabilitative technologies.
• RESNA also provides listings by state of programs that provide assistive technologies.