|A page from the notebook.|
At the time, men who could not speak could not inherit property or make wills, and Alexander, who was born deaf, was from a noble family, so it was important that he learn to communicate. His family turned to John Wallis and William Holder, and the teenager eventually learned to speak. Interestingly, the success of the case led to division between the two men as they argued about who had been successful with his instruction.
According to MSNBC, in 2008 a notebook was discovered in Berkshire, revealing that Wallis was the more successful tutor, and made use of verbal communication, writing, and sign language to communicate with Popham. He took a very scientific approach, which is interesting for the time period, when modern scientific research was just coming into being.
While I was reading about Alexander Popham, I discovered some mentions of a book about his notebook called Alexander Popham's Notebook by Peter W. Jackson, due to be published this year, but it doesn't appear it has come out yet.
For more information
300-year-old manual shows effort to help deaf speak (LiveScience)
Find could end 350-year science dispute (BBC News)
William Holder and John Wallis (Wikipedia)