Sound changes fall into two types: descriptive sound change and historical sound change.

音变分为描写音变与历史音变两大类。

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Descriptive sound change consists of changes in sound flow, sound position and some other non-phonetic aspects while historical phonetic change is divided into two subtypes.

描写音变又包括语流音变、位置音变与非语音原因的音变；历史音变则分为有规律的演变与特殊的变化两小类。

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