How did Helen Keller acquire speaking skills?

Miss Sarah Fuller had a method for teaching the deaf to speak, and she taught Helen herself.

Miss Fuller's method was this: she passed my hand lightly over her face, and let me feel the position of her tongue and lips when she made a sound. I was eager to imitate every motion and in an hour had learned six elements of speech: M, P, A, S, T, I. Miss Fuller gave me eleven lessons in all. I shall never forget the surprise and delight I felt when I uttered my first connected sentence, "It is warm." True, they were broken and stammering syllables; but they were human speech. My soul, conscious of new strength, came out of bondage, and was reaching through those broken symbols of speech to all knowledge and all faith.