“This sensorimotor interplay, movement and contact, is the basis for learning any new skill. This is what is going on, for instance, when infants are indulging in the endless exercise of vocal movements—spitting, smacking, blowing, cooing—what we call “babbling.” In the course of these vocal tract gestures, [the infant] produces sound patterns which resemble the vowels and consonants of his parents’ language as well as those of many foreign languages. Most importantly however, he is being flooded with sensory feedback. His every unintentional variation of vocal pitch, quality, or loudness, every movement of the tongue or lips in the midst of a vocal sound, produces simultaneous changes in sound and in tactile-proprioceptive sensation. Perhaps one reason why infants can master some simple speech movements, complex as they are, by nine or ten months is simply this fact of inevitable, simultaneous auditory and tactile-proprioceptive feedback from the vocal tract.5 Children who have poor sensation in their mouths and lips do not learn to talk normally, no matter how much training they are given. “To learn normal motor patterns for speech a child must not only hear the speech of others, but also he must hear and feel his own speech movements.”6”