Sunday, January 22, 2012

VOCAs: Assistive Technology for People with Speech Impairments

“More important than the right to speech is the right to speak.” The world renowned British theoretical physicist Stephen Hawking knows this exactly to be true.

Having been robbed of his ability to speak to a motor neuron disease, Stephen Hawking had to struggle with crude communication systems just to be able to tell his wants and needs…until he discovered VOCAs.

If it had not been for VOCAs, Stephen Hawking’s insights into the nature of space and time would not have been known.

This assistive technology has allowed him to communicate, write and publish his works, and give lectures to live audiences around the world in spite of losing his ability to speak.

In this post we will explore what VOCAs are and how these instruments give people an ability that most of us take for granted.

What are VOCAs?

VOCAs refer to voice output communication aids. These are electronic devices used by people who are either unable to speak or whose speech is difficult to understand.

VOCAs are used for augmentative and alternative communication (AAC). The term refers to different communication methods used by people who are unable to speak, have difficulty speaking, or have restrictions in understanding spoken or written communication.

Who uses VOCAs?

VOCAs are used by people who have limited or absent speech to communicate with the people around them. These include people who suffer from neurological disorders, such as autism, cerebral palsy, multiple sclerosis, and epilepsy.

VOCAs are also used to help an individual regain his ability to speak that might have been lost due to stroke, brain damage, or a motor neuron disease. An example of a motor neuron disease is Amyotrophic Lateral Sclerosis, which Stephen Hawking was diagnosed with.

Are there different types of VOCAs?

Just as there are different types of people who use VOCAs, there are also different types of VOCAs. These vary in all shapes, sizes, and complexity.

Dedicated Communication Devices vs. Communication Software Programs

VOCAs may be dedicated communication devices or laptop computers with specialized software installed.

Dedicated communication devices are designed primarily for communication, while computer based VOCAs are typically programmed to include additional features, such as an environmental control system.

An environmental control system allows the VOCA user to independently turn on electronic devices, such as the lights or television, via remote control.


Some VOCAs use digitized speech or a recorded natural speech of a person for voice output. Frequently used words, phrases, or sentences are recorded and stored into the device by somebody else other than the VOCA user. The VOCA user then pushes a button or turns a switch to play the message.

A VOCA with digitized speech can only say what someone has already recorded into it. However, they are easier to program than the VOCAs that use synthesized speech.

VOCAs that use synthesized speech make use of a speech synthesizer to produce artificial speech. These VOCAs use text to speech systems. This type of device is more flexible because users are not dependent on pre-recorded messages on their device. The speech synthesizer can say any combination of words, phrases, or sentences that the user chooses.

Representation of Messages

VOCAs may use text-based or symbol-based programs to represent messages on the device. Symbol-based VOCAs use pictures or symbols to represent messages which are supplied through symbol organizational systems. This type of device is typically used by individuals whose literacy level makes it difficult for them to use text-based VOCAs.

Text-based VOCAs typically have a keyboard for entering messages. They often feature a “word prediction” facility which helps reduce the number of keystrokes a user has to make. It also functions as a support tool for people whose spelling is not consistently reliable.

How are VOCAs accessed and controlled?

VOCAs can be adjusted according to its user’s needs.


Some people that use VOCAs have fine motor skills and they are able to press buttons on the devices. Adjusting the sensitivity of buttons and keyguards can help VOCA users that may have limited motor skills. Keyguards are plates that sit above the buttons of a VOCA device or a keyboard. They help the user to press the right key with more precision.

People that have limited fine motor skills input messages to a VOCA device through visual scanning. This technique is used by Stephen Hawking. Professor Hawking uses a switch to move through the letters on an onscreen grid. He then presses the switch to select the letter that he wants.

Other Access Methods used in VOCAs

Other access methods include:
  • a standard mouse;
  • mouse that can be controlled by the head;
  • joysticks; and
  • rollerballs.
It is truly hard to imagine living a life of silence, where your thoughts and dreams stay locked within you. VOCAs have given people with communication problems the freedom to express themselves and live life fully.

No comments:

Post a Comment