The hearing of newborns is different from that of adults, whose average hearing is within 26 dB, while that of newborns is 60-70 dB. Infants born less than 1 month old will have a startle (shiver) at sudden loud sounds. If they are sleeping, they will open their eyes; if their eyes are open and the sound is not too loud, they will close their eyes for a while. Infants 1 month of age are startled by sudden noises, accompanied by hand waving or stretching; close their eyes when they hear sudden noises during sleep; stop crying when they hear sudden noises. 3 months old Infants will close their eyes and move their fingers when they hear a sudden sound during sleep, but most of them will not have a whole body startle; turning on the radio or TV will cause the child to turn his face or eyes; the sound of quarrels, teasing, singing or music will cause the child to have a restless, joyful or disgusted expression. 5 month olds When the alarm clock is brought close to the ear and a ticking sound is heard, the child can turn his or her head toward the alarm clock and can better distinguish the voices of acquaintances and respond accordingly; hearing sudden loud noises can cause the child’s whole body to startle, cling to adults, or cry. 7-month-old infants can track sounds; turn their heads immediately to find the source of a radio or television sound; speak or sing to their children and they will stare at you quietly and occasionally make a sound to “answer”; actively search for sounds coming from the next room, outdoor animals, or other loud noises. Nine-month-old infants can giggle and imitate animal calls; show concern for outside sounds (e.g., cars, rain, airplanes); retract their outstretched hand or cry when they hear a reprimand such as “no” or “put it down”; hear a “come” or “go” sound. When they hear familiar sounds such as “come” or “goodbye,” they can act accordingly to the adult’s instructions, and they can bring very small sounds (such as a watch) close to their ears and turn their heads to look for them. 11-month-old infants can imitate adult voices, such as “mommy” and “baby”; they can sway their bodies to the beat of music; they can understand familiar words, such as “Give me xxx “, “Where is xxx” and respond accordingly. 12-15 months old Infants and toddlers can tilt their heads to listen attentively when there is a sound in the next room; can understand simple phrases and respond accordingly. They can point out their eyes, ears, mouth, and other body parts according to the adult’s questioning. Auditory behavioral responses are mainly manifested as: eye turning toward the sound source, searching for the sound source, facial expression change (surprise, laughing, crying), movement change or speech behavior change, etc. If an infant does not have an auditory response to 65dB of speech sounds, it can be considered abnormal.