Editing Infant (section)

===Response to sounds===
Infants respond to the sound of snake hissing, angry voices of adults, the crackling sound of a fire, thunder, and the cries of other infants. They have a drop in heart rate, their eyes blinking, increased turning toward the speakers or parent, all of these indicating that they were paying more attention. This is believed to be an evolutionary response to danger. Babies' ability to accurately locate sounds is refined during their first year.<ref>{{cite journal |last1=Erlich |first1=Nicole |last2=Lipp |first2=Ottmar V. |last3=Slaughter |first3=Virginia |title=Of hissing snakes and angry voices: human infants are differentially responsive to evolutionary fear-relevant sounds |journal=Developmental Science |year=2013 |volume=16 |issue=6 |pages=894–904 |pmid=24118715 |doi=10.1111/desc.12091 }}</ref>