人们很早就注意到语音的变化,例如汉代王充说:“古今言殊,四处异谈”,刘熙说:“古者曰车,声如居……今曰车,声近舍”,他们已经认识到同一个字的古今读音是不同的。但是,把语音变化作为一种规律来研究,则是很晚的事了。前一个世纪建立的历史比较法,就是通过亲属语言的历史比较来研究语音的发展历史。开始的时侯,语言学家们并不认为语音的变化一定是无例外的。但是后来,随着这些例外一个个地被新的语音律所解释,特别是 Karl·Verner 解释了 Grimm 定律中的例外以后,人们开始设想语音的变化是非常规则 People have noticed the changes of the voice very early. For example, in the Han Dynasty, Wang Chong said: “Ancient and modern sayings and different conversations”. Liu Xi said: " It has been recognized that ancient and modern pronunciation of the same word is different. However, it is very late to study phonetic change as a law. The historical comparative law established in the previous century is to study the history of the development of speech through the comparison of the history of relative languages. At the beginning, linguists did not think that the change of speech must be without exception. But later, as these exceptions were explained one by one by the new phonetic system, especially after Karl Verner explained the exceptions in Grimm’s law, one began to envisage that the phonetic changes are very regular