A man robbed of his ability to speak by ALS has told his wife 'I love you' again after an experimental chip implanted in his brain transformed his thoughts into words.

Terry Mandable had watched his voice gradually disappear as the devastating neurological disease progressed, leaving the once-outgoing professional struggling to communicate with the people closest to him.

But in an extraordinary glimpse of technology that could one day transform the lives of people unable to speak, Mandable has effectively been given his voice back.

An experimental chip by Neuralink was implanted in the speech motor region of his brain and detects neural activity as he attempts, and eventually simply thinks about speaking.

Artificial intelligence then decodes those signals, turning his intended words into text and speech through a computer.

During one deeply emotional demonstration, Mandable looked toward his wife, Lori, and thought three simple words.

'I love you.'

The words appeared on a screen before being spoken aloud. It was an overwhelming moment for Lori who appeared astonished at what she had just heard.

'You're thinking the words? And they're popping up?' she marveled. 

The remarkable breakthrough came after ALS had steadily stripped away something that had always been central to her husband's personality.

'Terry is an extrovert,' Lori said. 'He loves to talk, and it is heartbreaking to see what he's going through.'

Mandable had been thriving professionally before his diagnosis, having recently been made partner at his company and reaching what his wife described as 'the apex of his career.'

But then came the first worrying signs.

'He would come home from a business dinner and his speech would get slurred,' Lori recalled. 'At first I would joke with him. I'm like, "Oh, how much wine did you have with dinner?"'

'And he would look at me and go, "I didn't have any wine."'

As his condition worsened, communicating with clients and colleagues became increasingly difficult.

Mandable was eventually placed on long-term disability and forced to retire from the career he had loved.

His deteriorating speech also began changing life at home.

'He's getting to a point where I'm having trouble understanding more and more of what he's saying on a regular basis,' Lori said.

'That's one of my biggest fears, is that I'll lose that ability to communicate with him and know instinctively what he's needing.'

Mandable himself described the enormous toll of losing his speech, saying: 'Losing my voice has affected me in a lot of ways.

'I hope this will allow me to be a part of the conversation again.'

That hope led the couple to Neuralink's experimental Voice study, in which Mandable became the third participant.

The company, owned by Elon Musk, is developing a brain-computer interface that can detect signals produced by the brain and use algorithms to interpret what a participant intends to say.

The device remains experimental and is not FDA-approved for general use, meaning considerably more research will be required before technology like it could potentially become widely available.

For Mandable, the study offered something priceless.

'He needs to have his voice, and this can give him that,' Lori said. 'The more we learned about the study, and what this would mean to him, it just seems like it's a no- brainer.'

After agreeing to take part, Mandable underwent surgery to have the Neuralink device implanted.

Researchers then connected to the implant and examined the signals being produced by his brain.

The system uses thousands of channels to capture neural activity, with researchers focusing on the speech motor region and looking for changes when Mandable attempted to speak.

When they asked him to try a 'hello world,' his neural activity immediately lit up.

'Okay, that's pretty colorful,' a member of the team remarked. 'This is already super exciting to see, like how much activity lights up when you try and do different things.'

Detecting Mandable's brain activity was only the beginning.

Researchers then needed to train a decoder capable of translating his neural signals into his intended speech.

He was shown sentences and instructed to attempt to say them as best he could - even if the people around him could not understand the sounds he produced.

'Our understanding doesn't matter,' a researcher explained to him. 'All that matters are your brain signals and your intention.'

Mandable worked through sentences as the system learned the patterns generated by his brain.

Eventually, the technology began producing recognizable language.

In one stunning demonstration, the computer declared: 'Hello, how are you doing today?'

'You just got your voice back,' Mandable was told.

The experiment then reached another incredible stage when instead of struggling to physically produce the words, he could simply think them.

'Getting back to normal life, is what having Neuralink is all about.' Mandable said.

For Lori, the significance went far beyond an impressive technological demonstration.

'That impact of giving him his speech back has been remarkable,' she said, describing it as restoring 'a piece of his life' that had always been an integral part of who he was.

'With ALS, you start learning about what your priorities are, and it does put a lot of things into perspective,' she added.

'What this means for him and for us - something that I know I took for granted - to just be able to have a conversation with my husband, this means the world to us, to be able to have that communication back.'

Watching the screen respond to what was happening inside her husband's brain, Lori could barely contain her amazement.

'Oh, my gosh, that is so cool,' she exclaimed.