Normal auditory development in infants and toddlers Less than 1 month: startles once at a sudden loud sound; opens eyes if sleeping; closes eyes for a moment if they are open and the sound is not too loud. 1 month: startles to sudden sounds, accompanied by waving or stretching of the hands; opens eyes and cries when sleeping; closes eyes for a moment when lying down with eyes open; stops crying when crying when hearing sudden sounds. 3 months: Closes eyes tightly and moves fingers when hearing sudden noises during sleep, but most do not startle the whole body; turning on the radio or television causes the child to turn his or her face or eyes; sounds of arguing, teasing, singing, or music cause the child to show joyful, disturbed, or disgusted expressions. 5 months: Holds an alarm clock close to his or her ear and turns his or her head toward the clock when hearing a ticking sound; can better recognize and respond accordingly to the voices of acquaintances; will stop crying when hearing sudden noises. Can recognize familiar voices well and respond accordingly; when hearing sudden loud noises, the child will be shocked, hug an adult or cry. 7 months: Able to track sounds; can turn his head immediately to find the source of a radio or TV sound; will stare at you quietly and make sounds to “answer” when spoken to or sung to; can actively search for sounds coming from the next room, outdoor animal calls, or other loud noises. 9 months: giggles and imitates animal calls; expresses concern for external sounds; retracts outstretched hands or cries when hearing “no” or “put down”; cries when hearing “come” or “bye-bye”. When hearing familiar words such as “come” or “bye-bye,” these children can act accordingly to adults’ instructions; they can turn their heads to look for very small sounds when they hear them close to their ears. 11 months: Can imitate adults’ pronunciation of words such as “baby”; can move their bodies to the beat of music; can understand familiar words. 12 to 15 months: Cocks head and listens attentively to noises in the next room; understands simple phrases and responds accordingly. These children can point out their eyes, ears, nose, mouth, and other body parts when asked by adults.