Before using his famous voice synthesizer, Stephen Hawking continued to communicate verbally despite the progression of ALS, which he was diagnosed with in 1963. By the late 1970s, his speech had become increasingly difficult to understand due to the effects of the disease. As his condition worsened, a tracheotomy in 1985, following a severe bout of pneumonia, left him unable to speak altogether. This led him to adopt a voice synthesizer in the early 1980s, which became his primary means of comm

Stephen Hawking first appeared on the BBC in the 1977 documentary The Key to the Universe: The Search for the Laws of Creation | BBC Archive