When Eliza Doolittle demands to see what Professor Henry Higgins has been writing about her, in the beginning of the movie, he shows her his notebook, which she cannot read. The notation in the notebook is "Visible Speech", a phonetic notation invented by Alexander Melville Bell (father of Alexander Graham Bell) and extended and used heavily by Henry Sweet, a real-life phonetician and apparently the basis of the Professor Henry Higgins character.