the symbol ˇ , used over some letters in some languages to shows that the letter has a different pronunciation

He is responsible for introducing the use of diacritics, especially the háček, into Czech spelling in order to represent each sound by a single symbol. 他将变音符号引入到捷克语的拼写中，尤其是抑扬符的使用确保了每个发音由单一字母来代表。