Hearing
The hearing of the infant is very acute, although it is asserted that the child is unable to hear for the first twenty-four hours after birth. This is due to the absence of air in the middle ear. During the process of respiration air is gradually admitted to the middle ear and hearing becomes very acute, so much so that sharp noises will startle the child. For this reason the nursery should be so located that it may be as free as possible from noise. Noise is trying on the nervous system and should be avoided as far as possible. As early as two months of age the infant will turn his head in the direction of the noise.