The Latest Options in Speech Generating Devices


Linda Wasmer Andrews

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More than 2 million Americans are speech-impaired because of a severe communication disorder. Today, a growing number of these individuals have found their voice through speech generating devices (SGDs)—electronic devices that talk for them. Several recent advances in SGD technology have made the devices even more powerful and accessible. Here’s a quick look at some of the innovative new features that are available.

Look Who’s Talking

The simplest SGDs use digital speech—words or sentences that have been prerecorded by a human speaker. Specific messages can be retrieved and played back as needed. Such devices work well for many people. But for some, having to rely on a limited number of set messages is too confining.

That’s where text-to-speech SGDs come in. Users type what they want to say, and the device figures out how to pronounce the message using a complex set of rules for that language. The device then “speaks” the words using synthesized speech—an artificial simulation of the real thing. It doesn’t quite sound human, but it’s close. Think of how a GPS sounds, and you’ve got the idea.

“Text-to-speech SGDs continue to get better and better as the years go by,” says David Beukelman, Ph.D., professor of communication disorders at the University of Nebraska-Lincoln. Today they’re available in a host of languages. Some devices are even bilingual.

One Look Can Say It All

With SGDs, the machine may be doing the talking. But it’s the user who chooses what is said. Typically, this is done by typing on a keyboard, touching a screen, rolling a trackball, or tilting a joystick. But for users with very limited mobility, there are other options as well.

Eye tracking uses a sophisticated camera system to track the glint in a user’s eye. This allows the system to see where the person is looking on a screen. Then it directs a cursor to that location. After the user’s gaze has stayed on the same location for a set time—typically, somewhere between one-quarter-second and one second—the cursor clicks on that spot. In some systems, a blink can also activate a click. In this way, the user can select letters, words, or symbols to create a message.

Head tracking is similar. But rather than following the gaze of the eyes, a specialized camera tracks the movement of a small, disposable reflective dot that sticks to the user’s forehead or glasses. The user is then able to point and click a cursor with head movements. In essence, the “head dot” works like a wireless mouse.

The newest twist, which is called brain-computer interface (BCI), is still experimental and sounds like something straight out of a sci-fi novel. The user wears a cap with electrodes on it. These electrodes are attached to an EEG machine, which tracks electrical activity inside the brain. “The person looks at a screen that’s flashing letters very quickly. When the desired letter flashes, the person’s EEG changes,” says Melanie Fried-Oken, Ph.D., professor and director of the Assistive Technology Program at Oregon Health and Science University. This triggers the SGD to select that letter. Dr. Fried-Oken is one of the researchers studying this new technology. She says it shows great promise for helping those who can’t voluntarily move any part of the body, sometimes even the eyes.

The Need for Speed

For people who would otherwise find it difficult or impossible to express themselves through speech, SGDs can be life-changing. Yet the devices are still slower than ordinary conversation. To address this problem, many SGD features are aimed at reducing the number of keystrokes needed to create a message.

Word-prediction software predicts what someone is going to type from the first few keystrokes. Then it offers the rest of the word or phrase so the user doesn’t have to type the whole thing. You may have seen this at work in mobile phones, many of which use word prediction to speed up texting.

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Medical Reviewers: William C. Lloyd III, MD, FACS Last Review Date: Apr 15, 2017

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Medical References

  1. Everyday Life with ALS: A Practical Guide. Muscular Dystrophy Association.
  2. Information for AAC Users. American Speech-Language-Hearing Association.
  3. What is AAC? International Society for Augmentative and Alternative Communication.

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