There are few scientists that have captivated the public interest as much as renowned British physicist Stephen Hawking. His theories about black holes, his book A Brief History of Time, and his appearances on the Simpsons and Star Trek have made him an international icon for intelligence and science. And although it seems to make little difference to his colleagues or friends, there's no denying that part of Hawking's fame comes from the manner in which he communicates: a computer generated voice.

Struck by motor neuron disease (ALS/Lou Gehrig's), the brilliant professor has lost most of his muscle control, and a necessary tracheotomy has removed his ability to speak on his own. If Hawking had been born just a few decades earlier, the world would have lost all access to his insightful mind. Instead, custom devices (and commercially available software) have given him the means to express his revolutionary theories in physics.

Now, as Stephen Hawking's newest miniseries on the Discovery Channel is revealing some of his most startling thoughts on the universe and the future, we will take a look at the technology that allows him to talk. Make sure to catch the videos below.

How does stephen hawking speak
Stephen Hawking's voice is one of the most recognized in the world...and it's synthetic. A tiny IR sensor lets him twitch his cheek to spell and speak words. Image Credit:

ALS/motor neuron disease affects around seven people for every 100,000. While there are some treatments for ALS, there is no known cure. We've seen good progress for stem cell therapies for Lou Gehrig's disease but they are still in trial. For Hawking, motor neuron disease was supposed to be a death sentence. He was told he had but a few years to live after his initial diagnosis. Now, almost 40 years later, his body may be in decline, but his body of work is still growing.

Hawking's battle with motor neuron disease has led to an uneven decline in his ability to communicate over the years. If you saw him speak on TV in the late 70s, early 80s, you probably saw his words interpreted by his former graduate students or assistants.

After his tracheotomy in 1985, however, Hawking had to find a new way of communicating. Walter Woltosz developed Hawking's first software program that allowed him to spell by clicking a button with his hand. The software, called Equalizer, would be developed with Woltosz's company Words Plus, and different versions arose, including EZ Keys which Hawking currently uses. With this software, Hawking was capable of writing at just four words a minute, but it became his portal to the outside world, and it is through this technology that he has written books, essays, and countless lectures.

Although "Stephen Hawking: Master of the Universe" (2008) delves into many aspects of his life, the universe, and everything, it also gets into further detail about his voice system.

David Mason, of Cambridge Adaptive Communication assembled the first computer that could run Equalizer on Hawking's wheelchair and convert the text to audible speech. At the time, Mason's device was some of the most advanced text to speech hardware ever made. Still, the voice that came from Mason's hardware was a little robotic and sounded vaguely American. But it worked well. After years of use, that voice has become inexorably tied to Hawking. For most of us, that voice is a hallmark of Hawking and his work.

Eventually, Hawking lost the fine control of his hand. Luckily, his assistant Sam Blackburn helped develop a custom fix: an IR sensor that triggers off of twitches in the cheek muscle under the eye. (Go here to hear Blackburn further explain the intricateness of the device and software that Stephen uses to select words and write sentences.)

Hawking's simplified typing method and synthetic voice are a central part of his life. As such, he has been loath to introduce changes to his setup. This means that while Hawking may be at the cutting edge of physics, his speaking technology really isn't. We've already seen spelling systems that don't require any muscle movement at all, but instead rely entirely on EEG readings. There are even systems which can directly embed electrodes in the brain and allow you to choose words to type/speak. If Hawking eventually loses facial control, he may have to switch to such a system, or an eye tracking cursor as Blackburn briefly mentions in the Master of the Universe video.

Hawking foam missiles
Hawking can also use his speech software to launch foam missiles - a gift from an assistant. Heck, you can't be serious all the time. Image Credit:

I think Hawking's use of text to speech systems presents a very interesting example of attitudes towards technology. For the personal devices we rely on day to day, we want reliability. That's probably an even bigger desire when you depend on a machine as your sole avenue of communication. So it's no surprise that in personal use of technology, Hawking seems somewhat conservative. Even when he was breaking new ground (with his first text to speech device) it was to solve a problem, not illustrate a point. Yet when discussing the future, Hawking is far from conservative - painting remarkable pictures of time travel, alien civilizations, and technology. Here's his latest series, Into the Universe, which is currently airing on the Discovery Channel:

There are thousands of people all over the world who are locked in, trapped in their own bodies. We've seen a few devices, such as Braingate, which may eventually allow you to control machines with your thoughts, and there's certainly some hope that advanced stem cell treatments may one day repair neurological damage.

Today, however, typing systems that track eye or muscle movements are really the go-to technology for those who are unable to talk or write. In the near future, such systems may seem horribly primitive, but Stephen Hawking demonstrates the amazing gift that they represent. If he had developed the worsening symptoms of motor neuron disease even just a decade earlier, the world would have lost out on many years of Hawking's scientific work and he would have suffered the tragedy of being unable to speak to the world. As our abilities to communicate with neurologically damaged people continue to improve we may find more brilliant minds waiting behind physically stricken bodies. For now, Hawking's visions of our universe continue to amaze me, and I can't wait to hear what his unmistakable voice describes next.

[sources:, BBC, Stephen Hawking Master of the Universe (2008), MND Association]

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