Apart from the four tones（ā，á，ǎ，à）, there is another tone in Chinese, which is short and light, known as “the neutral tone”. For example: māma妈妈，bàba爸爸.   The neutral tone in Chinese is not only a phonological phenomenon, but also a way to distinguish meaning. For example, the word“东西” refers to the directions east and west when read as “dōngxī”, but when read as “dōngxi”, it means “thing/stuff”. (From HSK 1)