顎化作用在國語中的發生規律是中古見組字和精組字後接前高元音或介音而產生的，以中古韻圖來看，二、三和四等都可以發生顎化，但顎化作用表現在國語中的語音規律並不嚴整，以上陳述僅能表現國語中顎化現象的大致梗概。在細部表現上，國語中其實存在許多規律的例外表現，舉例而言，梗攝開口二等在國語中不顎化，如「梗、客」等字；蟹攝合口四等在國語中也不顎化，如「惠、慧」等字。這些例外音變現象主要因爲語音環境的關係而不發生顎化，也就是聲母、介音、主要元音與韻尾的搭配關係限制了顎化的發展。從這些例外音變可知，在語音環境中，同時對一個語音產生作用力的語音演變規律可能不只一種，因爲語音環境的差異，語音的規律發生會產生互相牽制的作用，若語音環境中有其它規律同時作用，此時便會產生「語音演變規律的例外」。

Palatalization acts on Chinese Mandarin in the environment of *ki(見) and *tsi (精) series. In the rhyme tables, palatalization acts on the second, the third and the forth divisions (等). The statement above is a broad outline to the palatalization in Chinese Mandarin. There are a lot of exceptions of palatalization in the detail of Mandarin. For instance, the environment in 梗 she(攝), open(開口)and the second division (等) doesn't palatalize such words as "梗,客". The environment in 蟹 she, closed (合口) and the forth division doesn't palatalize such words as "惠,慧". The sounds in a syllable might obstruct the action of palatalization. The combinations among the consonant, medial, main vowel and the final could affect the rates that palatalization occurs. Consequently, as sound changes are conditioned by one another, exceptions thus occur if there simultaneously exits the influence of other changes in the sound environment.