After five years work:
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.Jonathan Wood, Hawking's communications tech, approached Eric Dorsey, the Silicon Valley lead engineer on the CallText team, for help:
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?They set out to find the source code:
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.
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.There were two problems. Hawking didn't like the samples, and the team didn't like the idea that Hawking's voice depended on Nuance's proprietary source code:
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.Hawking OK-ed some of the initial samples, then:
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. ... 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.
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 the 14th March, Hawking died.
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 without it.
Clearly, this was a special case that justified a lot of work. But it is a great illustration of the ability of emulation to rescue truly obsolete digital technology; a 30-year-old proprietary, single-function box cobbled together from disparate chips is an extremely challenging target.