[DECtalk] The Quest to Save Stephen Hawking's Voice
joshknnd1982 at gmail.com
Sun Mar 18 20:30:00 EDT 2018
Really? Eloquence is a fork of keynote? How can you say that?
Sent from Mail for Windows 10
From: Tony Morales
Sent: Sunday, March 18, 2018 19:25
Subject: Re: [DECtalk] The Quest to Save Stephen Hawking's Voice
They sound similar because they have a common ancestor--MITalk.
30. The MIT MITalk system, by Jonathan Allen, Sheri Hunnicutt, and Dennis Klatt, 1979.
32. The Speech Plus Inc. `` Prose-2000'' commercial system, 1982.
33. The Klattalk system, by Dennis Klatt of MIT, which formed the basis for Digital Equipment Corporation's DECtalk commercial system, 1983.
Audio samples from Klatt's History of Speech Synthesis.
On Mar 18, 2018, at 4:04 PM, Damien Garwood <damien at dcpendleton.plus.com> wrote:
You know, hearing the samples in that article, I can't say I would be surprised if DECTalk was almost a fork of that synth. Just like it sounds like Eloquence is a fork of Keynote, and ESpeak is a fork of Orpheus (if not the vocal properties, then at least the dictionary and stress rules).
Let us hope that this sees a resurgeance of interest on formant synthesis, as concat synthesis, which currently seems to be dominating the TTS market, just doesn't cut it for screen readers in my opinion.
As for Stephen Hawking. May he rest in peace, may his spirit be in a happier place, may his great work be remembered, may his confidence shine through others, may his battles for accessibility continue to be fought, and may his voice be preserved forever as a reminder of the progress that was made in his lifetime in order to live a rich and fulfilling life despite his disabilities.
-----Original Message----- From: Jayson Smith
Sent: Sunday, March 18, 2018 10:04 PM
To: DECtalk Discussions
Subject: [DECtalk] The Quest to Save Stephen Hawking's Voice
Here's an interesting article I thought some of you might like.
The quest to save Stephen Hawking's voice
How a Silicon Valley team helped rebuild his distinctive robotic sound
By Jason Fagone
Eric Dorsey, a 62-year-old engineer in Palo Alto, was watching TV
Tuesday night when he started getting texts that Stephen Hawking had
died. He turned on the news and saw clips of the famed physicist
speaking in his iconic android voice — the voice that Dorsey had spent
so much time as a young man helping to create, and then, much later, to
save from destruction.
Dorsey and Hawking had first met nearly 30 years earlier to the day. In
March 1988, Hawking was visiting UC Berkeley during a three-week lecture
At 46, Hawking was already famous for his discoveries about quantum
physics and black holes, but not as famous as he was about to be. His
best-seller, “A Brief History of Time,” was a week away from release,
and Californians were curious about this British professor from the
University of Cambridge, packing the seats of his public talks,
approaching him at meals. Hawking motored into buildings and onto stages
in a wheelchair with a seat of maroon sheepskin, zooming around with the
nudge of a joystick, grinning as he left journalists and his nurses in
When he spoke, it was in the voice of a robot, a voice that emerged from
a gray box fixed to the back of his chair. The voice synthesizer, a
commercial product known as the CallText 5010, was a novelty then, not
yet a part of his identity; he’d begun using it just three years before,
after the motor neuron disease amyotrophic lateral sclerosis stole his
ability to speak. Hawking selected bits of text on a video screen by
moving his cheek, and the CallText turned the text into speech. At the
start of one lecture, Hawking joked about it: “The only problem,” he
said, to big laughs, “is that it gives me an American accent.”
Dorsey was with Hawking for part of that trip, tagging along as a sort
of authority on the voice, explaining its workings to journalists. He
worked at the Mountain View company that manufactured the CallText 5010,
a hardware board with two computer chips running custom software.
An upbeat 32-year-old, Dorsey was quiet by nature, but driven. He had
joined Speech Plus as an intern, attracted by its mission to help the
voiceless and the disabled; now he led a team of engineers, and at least
20,000 lines of his own code were in the CallText, the product that gave
voice to the most celebrated scientist of his era.
“We are getting close to answering the age-old questions,” Hawking said
at the close of a lecture. “Why are we here? Where did we come from?
Thank you for listening to me.”
At the end of his California tour, the physicist gave Dorsey a signed
copy of his new book, his thumbprint pressed onto the inside cover.
Hawking returned to Cambridge, Dorsey to his life in California.
Twenty-six years went by before they would cross paths again.
In tech years, that is a millennium. The Internet happened. Silicon
Valley boomed, busted, boomed again. Apple, Amazon, Facebook, Google, Uber.
Dorsey, meanwhile, left Speech Plus, which went bankrupt and was sold to
a series of other companies. He got married and had kids. He joined a
Buddhist temple. He eventually left the field of speech technology
altogether, becoming an engineering leader at DVR maker TiVo.
Tech, he’d learned, moves so fast. “There’s a new iPhone every year,”
Dorsey says. “Everything just kind of gets buried in the dustbin of
history very, very quickly.”
That’s why, when an email from Cambridge University arrived out of the
blue in 2014, Dorsey was surprised. It came from Hawking’s technical
assistant, Jonathan Wood, who was responsible for Hawking’s
Wood explained something so improbable that Dorsey had trouble
understanding at first: Hawking was still using the CallText 5010 speech
synthesizer, a version last upgraded in 1986. In nearly 30 years, he had
never switched to newer technology. Hawking liked the voice just the way
it was, and had stubbornly refused other options. But now the hardware
was showing wear and tear. If it failed entirely, his distinctive voice
would be lost to the ages.
The solution, Wood believed, was to replicate the decaying hardware in
new software, to somehow transplant a 30-year-old voice synthesizer into
a modern laptop — without changing the sound of the voice. For years, he
and several colleagues in Cambridge had been exploring different
approaches. What did Dorsey think?
Thirty years old? He thought. Oh, my God.
It wouldn’t be easy. They might have to locate the old source code. They
might have to find the original chips and the manuals for those chips.
They couldn’t buy them anymore, the companies don’t exist. Solving the
problem might mean mounting an archaeological dig through an antiquated
era of technology.
But it was for Stephen Hawking.
“Let’s get it done,” Dorsey said.
The poet Longfellow once wrote that the human voice is “the organ of the
soul.” More than any other part of us, our voice expresses who we are,
and the smallest fluctuations swing meaning in ways that are hard for
computers to understand. You speak a sentence, and the intonation rises
or falls depending on whether you’re making a statement or asking a
question. You do it without thinking, but a computer has to make a guess.
Today’s synthesized voices, like Apple’s Siri, rely on prerecorded
libraries of natural sound. Voice actors record huge libraries of words
and syllables, and software chops them up and reassembles them into
sentences on the fly. But 30 years ago, computers could only produce a
“stick-figure version” of a human voice, says Patti Price, a speech
recognition specialist and linguist in Palo Alto.
Back then, she worked as a postdoc in the Massachusetts Institute of
Technology lab of Dennis Klatt, a tall, thin, opera-loving scientist
originally from Wisconsin. Klatt is the godfather of Hawking’s voice. He
blasted his own throat with X-rays to measure the shape of his voice box
as he articulated certain sounds, and then developed a software model of
speech, the Klatt Model, based on his own voice.
Speech Plus took Klatt’s model, improved on it, and commercialized it in
various products, including the CallText 5010. One of Dorsey’s
contributions was to write an algorithm that controlled the intonation
of the voice, the rise and fall of words and sentences. Speech Plus
would sell thousands of CallText systems, though many customers
complained that the voice sounded too robotic.
But Hawking liked it.
True, it was robotic, but he appreciated that it was easy to understand:
“noise-robust,” as Price explains. The shape of its waveform was more
like a series of plateaus than the steep mountain cliffs of human
voices, which fall off more sharply. The flattish slope of Hawking’s
voice made it cut through noise in amphitheaters and lecture halls. He
often began his speeches with the same line — “Can you hear me?” — and
the audience would respond with an enthusiastic “Yes!”
“It’s got a ring to it that sticks out,” Price says.
“It’s very intelligible,” Dorsey says. “You can listen to it for a long
time, and it’s not irritating.”
Hawking’s only complaint was that it didn’t have a British accent.
Over the years, as synthetic voices grew more natural, taking advantage
of faster chips and cheap storage, Hawking had chances to upgrade. In
1996, a Massachusetts speech technology company called Nuance, which had
acquired the remains of Speech Plus, upgraded the CallText with evolved
software code that made the voice sound fuller and faster, less robotic,
with shorter pauses between sentences — to the engineers, an obvious
They sent Hawking a sample of the new voice, thinking he’d be pleased.
He was not. He said the intonation wasn’t right. He preferred the 1986
voice, the one modulated by Dorsey’s intonation algorithm. Hawking would
stick with that one.
“I keep it because I have not heard a voice I like better,” he once
said, “and because I have identified with it.” He could change to a
smoother voice, but then he wouldn’t sound like himself.
“To Stephen, his equipment is like a part of his body,” said Wood, his
chief technical aide. “To upgrade him to a new piece of software or a
new piece of hardware … he’s having to change a physical part of himself.”
Starting around 2009, Wood and several others at Cambridge began trying
to separate Hawking’s voice from the failing CallText hardware. The
group would included Peter Benie, a computer guru at the university;
Pawel Wozniak, a local engineering student; and Mark Green, an
experienced electrical engineer with Intel, which had a long
relationship with Hawking.
One option they considered was tweaking a modern synthetic voice like
Siri to sound more like Hawking. But Siri-type systems rely on the vast
computer power of Internet clouds, and Hawking couldn’t be constantly
tethered to the Internet. Benie also tried a completely different
approach. He wrote a software emulator for the CallText — essentially a
program that would fool a modern PC into thinking it was actually the
old CallText. But the samples it produced didn’t sound faithful enough
for Hawking’s taste.
By the time Cambridge reached out to Dorsey in 2014, they were
investigating a third avenue: track down the old CallText source code,
now owned by Nuance, and port it to Hawking’s laptop, transplanting the
old voice into a fresh new body.
Was it possible? Dorsey had no idea. It depended on whether he could
find the source code, or, failing that, information that would let him
reverse-engineer the source code.
He started emailing colleagues he hadn’t seen in 30 years, asking if
they had any CallText bric-a-brac still laying around: boards, chips,
manuals. One guy found an actual CallText board in his garage. Others
located dusty schematics.
It had the feel of a mad scramble through an earlier era of technology.
But people everywhere leaped at the chance to help. “The goal is to save
his voice,” Dorsey said. “Once you go to somebody — ‘I need you to help
save Stephen Hawking’s voice’ — they immediately wake up.”
His closest collaborator in Palo Alto soon became Price, the speech
technologist who had once studied with Klatt, the godfather of Hawking’s
voice. She was a master at analyzing audio samples, comparing one to
another and using their audio fingerprints to reverse engineer how they
must have been created.
Dorsey’s archaeological quest for old code turned out to be a
frustrating one. No one at Nuance was able to find the source code from
the 1986 version of CallText. They did, however, find the code for the
upgraded 1996 version of the voice, on a backup tape in an office in
Belgium. After a few months of work, Nuance engineers got the code up
and running and sent a series of audio samples to Hawking’s team,
adjusting the program to try to match the 1986 voice.
It didn’t quite work. For one thing, the match was close but not
perfect. Hawking flagged subtle differences others had trouble
discerning. “It’s like recognizing your mother’s voice,” Price said.
“When you hear them over the phone, they say two syllables and you know
if that’s right or not.”
The other issue was that Nuance owned the code, not Hawking. The famed
physicist had always been intent on controlling the use of his own
voice. If the team avoided using proprietary software, Hawking was
likely to have more control.
At this point, they switched tacks and returned to one of their original
ideas: to emulate the CallText in software, similar to how PCs can
emulate old Nintendo games that aren’t sold anymore.
The CallText, of course, was a more intricate beast than a Nintendo,
driven by two obsolete and complexly interacting chips, one made by
Intel and the other by NEC. Building the emulator demanded heroic feats
of programming, intuition and high-tech surgery. The chips had to be
removed from a spare CallText board with tweezers and a screwdriver. An
emulator for the Intel chip had to be written from scratch, by Benie. A
separate emulator, for the NEC, was borrowed from an open-source
Nintendo emulator called Higan.
Then all these disparate pieces had to be glued together. It was a
little like doing a jigsaw puzzle in a dark room. One chip was passing a
mysterious packet to the other every 10 milliseconds. Why? What was in it?
For a while, it was tough going. Some of the audio samples were so poor
that no one dared play them for Hawking.
The breakthrough came just before Christmas 2017, when the emulator
finally started producing sounds that resembled the familiar voice they
had been chasing. It had some minor glitches, but according to Price,
the voice was an acoustical match to Hawking’s, the waveforms virtually
identical. The only perceptible difference was a lack of analog buzz.
“It’s like a clean and shiny scrubbed-up version of his voice,” Price says.
When Benie heard it for the first time, coming out of a computer instead
of Hawking’s voice box, he thought it sounded more American than
Hawking’s voice. It was just an aural illusion. Benie realized that
perhaps, whenever he saw Hawking speak, he had been mentally adding a
hint of Britishness.
Over the next weeks, in Cambridge and Palo Alto, the team members
continued to debug the new voice, feeding it snippets of old Hawking
speeches and sample texts full of random commas, listening to the results.
On Jan. 17, the team felt ready to demonstrate the new voice for
Hawking. Wood, Wozniak, and Benie went to Hawking’s home in Cambridge
and played him samples on a Linux laptop. To the team’s relief and
happiness, Hawking gave his blessing. It did sound like his voice.
They still needed to port the voice to the PC, so temporarily, Wood
loaded a version of the voice onto a miniature hardware board known as a
Raspberry Pi. He thought Hawking might want to evaluate the voice in
everyday life, and the Pi was the quickest way to get him up and running.
On Jan. 26, Wood took the Pi along to Hawking’s house and asked if he’d
like to try it out. Hawking raised his eyebrows, which meant “yes.”
The team put the Pi in a tiny black box, attached it to Hawking’s chair
with Velcro, and plugged it into the voice box. Then they disconnected
the CallText. For the first time in 33 years, Hawking was able to speak
Wood watched eagerly for Hawking’s reaction.
“I love it,” Hawking said.
For the next few weeks in private conversations, Hawking continued to
speak through the emulator and the Raspberry Pi, chatting happily with
friends and colleagues. Wood said, “It was a pleasure to be able to give
him something like that, that so many people have worked on for so many
All that remained, the final step in the project, was to get the PC
version, still a bit buggy, working smoothly. But after a few more code
revisions, it was finally bug-free.
“We had pretty much completed all the technical hurdles,” Dorsey said.
“Everybody felt, finally, this is it, it’s going to work, this is done.”
And that is when Hawking got sick, in February.
According to Wood, Hawking continued using the emulator until his final
days. He was able to talk with his loved ones and caregivers with the
new software on the Raspberry Pi. The last words he spoke while wired
into his chair, whatever they were, he spoke with a version of his voice
that lives only in code, potentially deathless bits and bytes.
Everyone on the project understood that Hawking might not live long
enough to get much use out of the emulator. He had been sick before, but
always recovered. In 2014, when Wood first contacted Dorsey, Hawking was
72. They decided, though, that his CallText boards could keel over in
six months, while Hawking might live to 80.
Along with sadness at Hawking’s death, Dorsey can’t help feeling some
disappointment. He and the team had raced for years to build a
complicated thing that had worked beautifully, but now sat idle.
At the same time, the project brought him back to his younger self, the
guy who wanted to use engineering to perform good deeds and help people.
All those years ago, working on the intonation algorithm in the
CallText, he couldn’t imagine that it would end up helping define a
genius of science to the world, and even to himself.
Tech changes fast. Most machines end up as dust, and when we die, our
voices die with us. Hawking’s voice is different. The original CallText
boards have passed to his estate, to use as his family wishes. So has
the new software, the CallText emulator, which can be ported to future
platforms as they are invented.
Hawking was, famously, an atheist, skeptical of the afterlife; “We have
this one life to appreciate the grand design of this universe,” he once
said, “and for that, I am extremely grateful.” But there is no longer
any physical reason his voice can’t live forever.
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