The first embryonic cells are sound sensitive. By about one and a half months in the womb, a baby’s auditory system is virtually complete. Every cell in the developing fetal body is influenced by the energy reflected in sound waves. Once the baby is born, the melodies of speech are also vital to communication between mother and infant. Diane Deutsch, Professor of Psychology at the University of California, says that parents often use exaggerated speech patterns when communicating with their babies. Sometimes known as "motherese," these exaggerated speech patterns differ considerably between languages. The auditory pathways continue to develop until age 7-10 years. According to Jane M. Healy, PhD, author of Your Child’s Growing Mind, Music, human speech, and environmental sounds are all important in a child's balanced auditory diet.