Susan Schaller who wrote A Man Without Words on Radio Lab.
From the book’s description on Amazon:
“For more than a quarter of a century, Ildefonso, a Mexican Indian, lived in total isolation, set apart from the rest of the world. He wasn’t a political prisoner or a social recluse, he was simply born deaf and had never been taught even the most basic language. Susan Schaller, then a twenty-four-year-old graduate student, encountered him in a class for the deaf where she had been sent as an interpreter and where he sat isolated, since he knew no sign language. She found him obviously intelligent and sharply observant but unable to communicate, and she felt compelled to bring him to a comprehension of words.”
The transcript is here.