What Happened to Stephen Hawking: ALS, Voice, and Death

Stephen Hawking was diagnosed with amyotrophic lateral sclerosis (ALS) at age 21, lost the ability to speak naturally by his mid-40s, communicated for decades through a computerized voice system controlled by his cheek, and died on March 14, 2018, at the age of 76 in Cambridge, England.¹ His survival with the disease spanned more than 50 years, an outcome so rare that it puzzled neurologists throughout his life and continues to provoke questions about ALS itself.

The Diagnosis and What ALS Does

Hawking began noticing clumsiness and slurred speech as a graduate student at Cambridge in the early 1960s. He was diagnosed with ALS in 1963, shortly after his 21st birthday, and was initially told he had roughly two years to live. ALS attacks the motor neurons that control voluntary movement, progressively destroying the ability to walk, use the hands, swallow, and eventually breathe. The disease does not, however, directly affect cognition, which is why Hawking could continue his theoretical physics work even as his body deteriorated.²

By the late 1960s, Hawking needed a wheelchair. Over the following decades, his muscle control progressively narrowed. He lost the use of his hands, then lost the ability to write on a blackboard. His speech grew increasingly difficult for anyone except close family and colleagues to understand. By 1985, a bout of pneumonia during a trip to CERN in Geneva led to an emergency tracheotomy that saved his life but permanently removed his ability to speak. From that point on, every word he “said” came through a machine.

Why He Survived So Long

Hawking’s 55 years with ALS is extraordinary by any measure. The median survival from symptom onset to death for ALS patients ranges from about 20 to 48 months, depending on the study and the population measured. That means most people diagnosed with the disease die within two to four years. Yet roughly 10 to 20 percent of patients survive longer than a decade, and a small fraction live much longer than that.³

One of the strongest predictors of longer survival is young age at onset. Patients whose symptoms begin before age 40 tend to have a significantly better prognosis and often survive beyond 10 years.³ Hawking’s symptoms appeared in his early 20s, placing him squarely in this younger-onset group. But even among young-onset patients, surviving five decades is vanishingly rare, and no single explanation fully accounts for it.

Neurologists have speculated that Hawking may have had an unusually slow-progressing form of the disease, sometimes classified informally as a benign variant. The fact that his early symptoms primarily affected limb function rather than breathing or swallowing may also have bought him time. ALS that starts in the limbs (called limb-onset) generally carries a somewhat better prognosis than ALS that begins with difficulty speaking or swallowing (bulbar-onset). Still, Hawking himself acknowledged that he did not know why he survived so long and considered himself fortunate.

How His Voice Worked

The robotic voice that became Hawking’s global trademark was never his own. After the 1985 tracheotomy took away his natural speech, a computer scientist named Walter Woltosz provided him with a program called Equalizer, which ran on a desktop computer attached to his wheelchair. Hawking initially operated the system by clicking a handheld switch to select words from menus on a screen. The chosen words were then spoken aloud by a speech synthesizer, a hardware unit made by a company called Speech Plus. That synthesizer produced the distinctive flat, American-accented robotic voice the world came to associate with Hawking.

As his hand control deteriorated further, the input method had to change. Eventually, the only voluntary movement Hawking could reliably produce was a small contraction of a muscle in his cheek. An infrared sensor mounted on his glasses detected that cheek twitch and used it as the sole input for selecting letters, words, and commands on his screen.² A cursor scanned across rows and columns of options; when it reached the one he wanted, a cheek twitch selected it. One twitch at a time, he composed sentences, gave lectures, wrote books, and exchanged emails.

This was painstaking work. At his peak, Hawking could produce about 15 words per minute using the handheld switch. By the time he was relying on the cheek sensor alone, his rate had slowed to roughly one to two words per minute. To make this tolerable, predictive text became essential. Intel, which had been supporting Hawking’s technology needs since the late 1990s, developed a platform called ACAT (Assistive Context-Aware Toolkit) in partnership with SwiftKey, the company behind a widely used smartphone keyboard. The software learned Hawking’s vocabulary, writing style, and frequently used phrases, so it could predict what he was trying to say after just a few character inputs. Sensors in his glasses could also recognize movements of his mouth and eyebrows, giving the system multiple signals to work with beyond the cheek twitch alone.²

Hawking was offered updated, more natural-sounding voices over the years but consistently refused them. He had come to identify with the original synthesizer’s tone and felt it had become his voice. Audiences around the world recognized it instantly, and Hawking once joked that the American accent was preferable because it was better for getting dates.

The Role of Respiratory Support in ALS Survival

For most ALS patients, the primary cause of death is respiratory failure. The muscles that expand the chest and control the diaphragm weaken along with everything else, and without intervention, breathing eventually becomes impossible. Mechanical ventilation can extend life substantially, but it also changes the nature of living with the disease.

A large national study of over 1,300 ALS patients on home mechanical ventilation found that the type of breathing support made a significant difference to survival. Patients on non-invasive ventilation, which delivers air through a mask, had a median survival of about 1.7 years from the time ventilation was started. Those on invasive ventilation, typically through a tracheostomy tube, survived a median of about 4.9 years. Patients who began with non-invasive support and later transitioned to invasive ventilation survived the longest, with a median of about 6.5 years on ventilatory support.⁴

Hawking’s 1985 tracheotomy placed him on invasive ventilation, which he used for the remaining 33 years of his life. That decision, made in a medical emergency, was controversial at the time. His first wife, Jane Hawking, has written about the agonizing choice, noting that doctors had raised the possibility of simply letting him die. She insisted on the tracheotomy. The procedure meant Hawking would need 24-hour nursing care for the rest of his life, but it also meant he would go on to write “A Brief History of Time,” become the most famous scientist of his era, and live another three decades.

The survival numbers above come from a broader ALS population, and Hawking’s case was already an outlier before ventilation entered the picture. But the data illustrates an important general point: breathing support is the single most powerful medical intervention for extending life in ALS, and the choice between non-invasive masks and tracheostomy ventilation involves real tradeoffs in comfort, caregiving demands, and quality of life that patients and families have to navigate.

Newer Respiratory Options for ALS Patients

Not every ALS patient can tolerate the standard ventilation approaches. Non-invasive ventilation, while less burdensome than a tracheostomy, requires wearing a mask that some patients find intolerable due to claustrophobia, discomfort with the airflow, or difficulty adapting to the interface. A recent case series examined the use of high-flow nasal cannula (HFNC), which delivers warm, humidified air through nasal prongs, as an alternative for ALS patients who could not tolerate standard masks. Among 18 patients studied, about 39 percent had partial intolerance to non-invasive ventilation, and a third could alternate between short periods of mask ventilation and HFNC use.⁵

This is a small study and not yet a standard-of-care recommendation. But it reflects a broader trend in ALS medicine toward finding flexible solutions for patients who struggle with conventional equipment. Hawking had an enormous amount of financial and institutional support for his medical care, including a team of nurses and access to the best technology available. Most ALS patients do not have those resources, which makes comfort and tolerability of respiratory devices a more pressing practical concern.

How Hawking Died

Hawking died peacefully at his home in Cambridge on March 14, 2018. He was 76 years old.¹ His family released a brief statement but did not disclose a specific cause of death beyond the long-standing ALS diagnosis. Given that respiratory failure is the terminal event in most ALS cases, and given that Hawking had been on invasive ventilation for over three decades, the assumption among physicians was that his body’s reserves had simply been exhausted.

The date of his death, March 14, is Pi Day (3/14) and also the birthday of Albert Einstein, a coincidence that the internet noticed immediately. Hawking was 76, meaning he had lived with ALS for 55 years. His ashes were interred at Westminster Abbey, between the graves of Isaac Newton and Charles Darwin, during a memorial service in June 2018.

The Open-Source Legacy of His Communication Technology

One of the less-discussed outcomes of Hawking’s decades-long reliance on assistive technology is that the software built for him eventually became available to everyone. Intel released ACAT as open-source software on GitHub, making the platform freely accessible to developers worldwide. The hope, as Intel principal engineer Lama Nachman put it, was that “this open source configurable platform will allow developers to keep working by adding new interfaces, new sensors, improving the prediction system and adding many other features.”²

That open-source release has since been adapted for multiple languages, including French, Spanish, and Arabic, extending the system’s reach well beyond English-speaking users.⁶ The platform was designed to be configurable for different levels of disability, meaning it could be adjusted for people who retained more or less motor control than Hawking had in his final years. Someone with the ability to move a finger could use ACAT with a different sensor setup than someone limited to eye or cheek movements.

This matters because the population of people who need augmentative and alternative communication (AAC) devices extends far beyond ALS. People with cerebral palsy, locked-in syndrome, brainstem stroke, and advanced multiple sclerosis face similar communication barriers. The technology built for one very famous physicist has become a building block for a larger community of developers working on accessible communication tools.

Brain-Computer Interfaces and What Comes After Switch-Based Systems

Hawking’s communication system, despite its sophistication, was fundamentally limited by its reliance on a single physical input. One cheek twitch to make one selection. If that remaining muscle control had failed, he would have had no way to operate the system. This is not a hypothetical scenario for many ALS patients. As the disease reaches its most advanced stages, some people lose all voluntary muscle control, a state sometimes called locked-in syndrome, where the mind remains active but the body offers no reliable output channel.

Brain-computer interfaces (BCIs) represent the next frontier for people in that position. These systems detect electrical signals in the brain and translate them into commands without requiring any physical movement at all. One approach, the P300 speller, measures a specific brainwave response that occurs when a person sees a target letter flash on a screen. By detecting which flash triggers the response, the system can determine which letter the person is looking at and spell out words one character at a time. Research has found that with word prediction and optimized flash sequences, BCI systems can reach information-transfer rates competitive with eye-tracking devices, which are themselves a common communication tool for people with severe motor disabilities.⁷

BCIs remain slower and less reliable than Hawking’s cheek-operated system was, and they require more setup and calibration. But for patients who have lost all voluntary movement, they represent the only potential communication pathway. The gap between a system like ACAT, which requires at least one controllable muscle, and a BCI, which requires none, is the gap between being able to communicate and being locked in silence. Closing that gap is one of the most active areas of assistive technology research, driven in part by the visibility that Hawking’s own technology needs brought to the field.

Why Hawking’s Case Remains Scientifically Unusual

ALS researchers still do not fully understand why a small percentage of patients survive far longer than the median. The statistical reality is clear enough: most die within a few years, but a meaningful minority survive a decade or more, with younger onset being the strongest known predictor of long survival.³ What remains murky is the biological mechanism behind this variability. Some researchers have proposed that different genetic subtypes of ALS progress at different rates. Others have pointed to the specific motor neuron populations affected early in the disease, suggesting that patterns of spread vary between patients in ways that are difficult to predict from initial symptoms.

Hawking’s case is often cited as the most extreme example of long ALS survival, and it can create a misleading impression of what is typical. A newly diagnosed patient or their family searching for information about ALS may come across Hawking’s story and assume that decades of survival are more common than they are. The reality is that Hawking was an outlier among outliers. His case demonstrates that very long survival is biologically possible, but the combination of factors that allowed it in his case, including young onset, limb-first symptom progression, access to round-the-clock medical care, and what appears to have been an intrinsically slow disease course, is not something most patients can expect to replicate. Neurologists who treated Hawking have said that his survival was as much a mystery to them as it was to anyone else.

1
Clinical Medicine and Therapeutics. How Stephen Hawking Defied Amyotrophic Lateral Sclerosis for Five Decades
2
PubMed Central. ‘Intel Acat’ Assistive Platform for Arabic Speaking Disabled People: a Complete Integration – Section: Intel Assistive Context-Aware Toolkit (ACAT)
3
PubMed Central. Prognostic factors in ALS: A critical review – Section: Demographic factors
4
PubMed. Home mechanical ventilation for amyotrophic lateral sclerosis-a national study of survival and treatment trends across 27 years
5
PubMed Central. Use of High‐Flow Nasal Cannula in Amyotrophic Lateral Sclerosis Patients Intolerant to Non‐Invasive Ventilation: A Case Series
6
Medical Technologies Journal. Toward a Full Integration of the Arabic Language into ‘Intel ACAT’ Assitive Platform
7
PubMed. Brain computer interface with the P300 speller: Usability for disabled people with amyotrophic lateral sclerosis