It may or may not be normal for a three-month-old baby to not follow sight or sound. 1. Normal. Usually three-month-old babies can turn their head with their eyes and can turn 180° with the objects they see or the sounds they hear. However, if the baby has a hearing test at birth and passes it, proving that the baby’s hearing is normal, parents may not worry too much. Infants who do not follow sight or sound may be due to individual developmental differences, low sound levels that do not attract the infant’s attention, or lack of interest. Parents can use high-frequency sounds, rhythmic children’s songs, brightly colored objects to attract the baby’s attention. 2. Not normal. If the baby’s condition does not improve by the above methods, it is considered to be due to the backward development of the mental system. Three-month-old babies who do not follow their eyes and ears need to seek medical attention to identify the cause and intervene in a timely manner to avoid delays in their condition.