The Man with the Childlike Accent

Once upon a time the main character was afraid very much. Since then, he clearly does not speak a few letters, making him look like a baby babbling. He did everything to get rid of his illness, but to no avail. The doctor advised him such a therapy: go there where he was startled many years ago and try to get afraid there again. But what if he is an adult and is not afraid of anything children offer to him?