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Augmentative and alternative communication

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Dynamic Display: changes automatically on screen with user choice

The American Speech and Hearing Association's (ASHA) definition of an augmentative and alternative communication (AAC) system as "an integrated group of components, including the symbols, aids, strategies and techniques used by individuals to enhance communication". This article addresses some frequently asked questions regarding AAC.


What is a speech generating device (SGD)?

A SGD or communication device is used by an individual to enable him or her to communicate more effectively with others. A device assists an individual in communicating through printed words, speech or voice output, pictures, or any combination of these. Devices range from having basic components and performing fundamental language functions to having the ability to perform computer-like functions and control household appliances. SGDs are designed to be used as either a primary method of communication or a supplementary mode of communication to augment existing communication strategies and can be configured or customized to address most communication needs.

Who uses a SGD?

Individuals who cannot speak, are difficult to understand, or have language retrieval issues might use a SGD. Communication devices are used by people of all ages with a variety of disabilities. An individual with a communication impairment may have difficulty with expressive (what he or she can express) and/or receptive (what he or she understands) communication. Some possible causes of communication impairment include:

  • Acquired brain injury (e.g., stroke, accident, tumor, anoxia)
  • Spinal cord injury
  • Disease (e.g., cancer, amyotrophic lateral sclerosis, multiple sclerosis)
  • Other traumatic injury (e.g., burns, nerve damage)
  • Developmental causes (e.g., prenatal, perinatal, or postnatal trauma, congenital or genetic malformations)

What types of communication devices are available?

There are a variety of communication devices available. Devices can have a single message or multiple messages. Medicare categorizes devices based on the following features.

  • Speech Output - Digitized (recorded human speech) or Synthesized (electronic conversion of text into speech).
  • Message Type - Prerecorded (messages that are stored) or Message Formulation (can spontaneously create novel messages).
  • Recording Time - less than or equal to 8 minutes, greater than 8 minutes, or based on the memory size of the device in general (e.g., 16 MB).
  • Access Method - Direct Physical Contact with Device or Multiple Access Methods (e.g., switch, mouse, joystick, etc.).
  • Message Formulation Technique - Spelling only or Spelling and Other Methods.

Additionally, devices have different selection sets (dynamic, static or both). Dynamic sets are similar to a computer monitor. The selection set or level changes automatically on a dynamic screen as the user makes choices. Some dynamic sets can be activated by touch or through a pointing tool (e.g., stylus). Dynamic sets can be color or black and white. Typically, the information on these screens is difficult to see in places with bright lighting. These screens can also be damaged by misuse or accidental impact.

Static sets have fixed symbol choices or levels that can be manually changed. Most static sets are easier to see in brightly-lit situations, depending on the quality of the information you are displaying (e.g., photographs, text, etc.). Static sets usually have a group of letters, pictures and/or words on an overlay that is inserted or attached to the device. Spelling or keyboarding devices generally have static sets.

Figures 1,2: Example of a Static and Dynamic Display Communication Device

Static Display: fixed choices requiring manual change Dynamic Display: changes automatically on screen with user choice

How are messages created or formulated on the devices?

SGDs contain selection sets or symbols to represent language. Selection sets can be any combination of photographs, line drawings, text, objects (on some static display devices), or other graphic symbols. Symbols can vary in size and may be in color or black and white depending on the device. Symbols can represent entire messages (e.g., a picture of a toilet to represent "I have to use the bathroom"), phrases, single words or letters. Some symbols must be combined with others symbols to create words, sentences, or complete messages (e.g., semantic compaction).

Figures 3,4,5: Example of Semantic Compaction, Line Drawing, and Photograph

Semantic Compaction (might mean 'red') Line Drawing Photograph

Does a person need to be able to read to use a communication device?

Literacy is not required to use a SGD. Some devices require keyboarding, spelling, or word identification skills, but most devices have selection sets based on graphic symbols. Word completion and prediction is available on some devices and can assist an individual with spelling by offering choices of possible words. Additionally, voice output allows the user to hear the message and make corrections if it wasn't what he or she intended.

Does a person have to use his or her hands to operate a communication device?

Although some devices can only be accessed by directly pressing or touching, most communication devices will accept alternative input. The way in which a person physically selects the messages is called the Access Method. If a person is unable to directly select the message through pointing (with a finger, headpointer, mouthstick or other tool), he or she will need to use an alternative input device.

Alternative input devices include mouse emulators and specialized switches. A mouse emulator is a device that simulates mouse movements with the assistance of a driver or other software. Some examples of mouse emulators used with communication devices are joysticks, trackballs, and infrared pointers.

Specialized switches are used with the scanning feature on some devices. Specialized switches can be activated by almost any body part or body action. Some examples of specialized switches include sip and puff, myoelectrical, mercury, eye blink, and vibration.

Figures 9, 10, 11: Examples of Switches: Sip and Puff, "Twitch Switch", and "Jelly Switch" activated by direct face contact

Sip and Puff Switch Twitch Switch Jelly Switch activated by direct face contact

Scanning is a selection method that presents choices or messages in a sequence. To make a selection, an individual activates a switch when the choice or message is presented to make a selection. Scanning presentation can be through visual patterns, auditory cues, or a combination of both. Scanning patterns can vary depending on the skills of the individual. Typical patterns include: linear (choices or messages are automatically presented individually), row-column (rows are automatically presented, then each choice or message in that row is presented), and step (the individual uses his or her switch to step or scan through the choices or messages and then makes a selection with the switch). Scanning rate (how fast the items are scanned) and timing (the amount of time that the switch needs to be activated to make a selection) can also be adjusted according to the individual.

Figure 10. Example of Row-Column Scanning Pattern

Screenshot of Row-Column Scanning Pattern with Highlighted Row and Highlighted Letter

Two views of a communication device screen with 8 rows by 6 columns (48 choices). Using the row-column scanning pattern, rows are presented top to bottom (i.e. 3rd row with 6 choices: a,b,c,d,comma,l). Then, each column in that row is presented left to right (i.e. 3rd column with the letter 'c').

Will using a communication device stop someone from trying to talk?

There is research that supports the idea that using a communication device does not hinder the development or return of natural speech. In fact, most people using a device find it faster to use natural speech if they can be understood by others.

Is training required to use a communication device?

Most of the time, some form of training will be required before operating a communication device. Minimal training (e.g., how to turn it on, how to recharge it, etc.) will be necessary with most devices; however, some devices require more extensive training. The manufacturer or distributor of the device typically offers training. Local agencies, professionals, or experienced users familiar with SGDs may also be able to provide training. Funding is usually available for training through major funding entities.

Are there ways to help pay for a communication device?

There are some funding options for communication devices. A formal communication assessment performed by a Speech-Language Pathologist is usually required prior to seeking funding. A physician's prescription may also be required by some funding sources. The following are brief descriptions of funding options. Refer to the specific funding source for details. Some of these options can be combined.

Private Insurance

Some private insurance companies will fund SGD equipment. Prior authorization is usually required and coverage depends on the policy. The insurance company may need an explanation of what the SGD does. The insurance company may also need to be convinced of the medical necessity of the device.


Legally, schools are required to provide appropriate assistive technology services for students. The Individuals with Disabilities Education Act (IDEA, P.L. 101-476) and the 1997 amendment specifically address the inclusion of assistive technology in the Individualized Education Plan (IEP). Services must be provided at no cost to the parents if the IEP team determines that a student requires this type of assistive technology in order to receive a free and appropriate public education and designates the assistive technology as either part of special education or a related service.


The purchase of SGD equipment is typically covered for individuals up to age 21 in most states. Many states cover the purchase of equipment for individuals of all ages. However, each state varies as to their submission and coverage guidelines. Equipment manufacturers should be familiar with specific state funding practices and can assist in determining the documentation necessary for funding.

Division of Vocational Rehabilitation

The Individualized Plan for Employment (IPE) or comparable plan of action outlines the services provided through VR for the purpose of seeking employment. If a SGD is required to meet established goals, funding may be available.


SGDs are funded by Medicare for Medicare Part B enrollees who live in their own home or in an assisted living facility. Medicare requires that a Speech-Language Pathologist perform an evaluation that meets the guidelines according to the Regional Medical Review Policies (this information is available from the AAC-RERC).


Formerly known as CHAMPUS, Tricare is a health benefits program for dependents of active duty military service members and military retirees, but nowcovers SGDs for all program enrollees who require them. Congress explicitly directed the expansion of Tricare SGD coverage in the FY 2002 military reauthorization bill, signed by the President on December 28, 2001.

Telecommunication Equipment Distribution Programs (TEDP)

Many states have a TEDP that offers SGDs to individuals to enable access to home telephone equipment. These programs typically have eligibility requirements and specific equipment lists. States are not required to have a TEDP, not every program covers SGDs, and each state structures their TEDP differently.

How much do communication devices cost?

Devices range in price. Basic, single message devices cost anywhere from $10 to $100. Devices with more messages and/or more options can cost up to $8000 and more. Medicare has set cost guidelines for predefined device categories.

  • Devices with digitized speech and eight minutes or less of recording time = $399.27
  • Devices with digitized speech and greater than eight, but less than or equal to 20 minutes of recording time = $1220.91
  • Devices with digitized speech and greater than 20, but less than or equal to 40 minutes of recording time = $1610.55
  • Devices with digitized speech and greater than 40 minutes of recording time = $2361.53
  • Devices with synthesized speech, message formulation by spelling and physical contact with the device to access messages= $3651.72
  • Devices with synthesized speech, multiple message formulation methods and multiple access methods= $6910.38

Are there ways to try out communication devices?

The selection of a communication device can be a very difficult decision. It is always helpful to seek the assistance of an experienced Speech-Language Pathologist and/or Assistive Technology Practitioner for a complete and thorough evaluation. Be sure to investigate the features, support, and warranty of several devices before purchasing one. Additionally, research the funding options in your area and if possible, arrange to borrow the particular device for an extended period of time (typical loan or rental periods range from 2 weeks to 3 months).

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