You are running in the playground. But then suddenly，you fall and hurt yourself. "Ow!"you cry. This sound is very familiar to us all. Crying out when we get hurt is a natural action. But have you thought about why we shout it out？And do people from different languages make the similar sound？
Scientists now believe they've found out the reason：shouting the word"ow"partly stops pain messages from traveling to the brain. So by shouting it out，people can feel less pain.
The scientists tested how long volunteers could hold their hands in very cold water. In the first group，they were allowed to shout"ow"when they felt pain. In another group they had to stay silent. The results showed that volunteers were able to keep their hands in the cold water for longer when they were allowed to shout out. Shouting out"ow"helps humans feel less pain and add the time.
What's more，scientists have also found that different languages have similar expressions of pain. While cries of"ow"or"ouch"are heard in English，South Africans yell"eina"
These languages have one thing in common：when people shout them，the mouth simply opens，the tongue（舌头）（嘴唇） unrounded. It is a simple sound that requires little control，so it's easy to make a big sound. For the reasons
