The fanqie 反切 system of sound transcription is a traditional method to describe the sound of one character by using the initial and the final sound of two other characters. It is used in all traditional dictionaries, as well as in commentaries to books. The character whose pronunciation is to be transcribed is called zhuyinzi 注音字 "character to be commented phonetically", the two characters used to indicate the pronunciation are called beiqiezi 被切字 "cut characters".
The origin of the fanqie system goes back to the Han period 漢 (206 BCE-220 CE). It is said that a certain Sun Yan 孫炎 (220-265) from the Wei period 曹魏 (220-265), author of a phonetic commentary to the gloss book Erya 爾雅, had invented the system, but there is no proof for this statement. Song-period 宋 (960-1279) scholars like Shen Kuo 沈括 (1031-1095) and Zheng Qiao 鄭樵 (1104-1162), the late Ming-period 明 (1368-1644) scholar Gu Yanwu 顧炎武 (1613-1682), and the Qing-period 清 (1644-1911) scholar Liu Xizai 劉熙載 (1813-1881) were of the opinion that the fanqie system already predated the Han period.
The fanqie system might be a natural result of the fact that many words were disyllabic, either having syllables with a common initial consonant or syllables with common finals (assonances dieyun 疊韻, and alliterations shuangsheng 雙聲, respectively). The Republican scholar Zhang Binglin 章炳麟 (1868-1936) held that the fanqie system was still in a tentative state during the Later Han period and was regularly used by the scholars Fu Qian 服虔 and Ying Shao 應劭 (d. c. 203). Whoever the inventor was, the fanqie system was an important supplement to much more simpler systems of transcription, like rending the sound of a character by presenting a homophone, like A du ruo B 甲讀若乙 "A is read like B", or A zhi yin B 甲直音乙 "A is just pronounced as B".
In the fanqie system, the pronuncation of the character 冬, for example, is explained by the expression du zong qie 都宗切, meaning "cut" the characters 都 and 宗 into initials and finals, take the initial sound of the first ([d-]) and the final sound of the second ([-ʊŋ˥˩]), including its tone pitch, put these together, and the result is the pronunciaton of the character to be explained ([dʊŋ˥˩]).
Some characters used as indicators of the final sound have no modern initial consonant (like 魚欲切 [ŋ(-ĭo˩)] and [(j-)ĭwok, modern yù] for 玉 [ŋĭwok, modern yù]), but as seen in the example, this is not necessarily the case. Characters without initial consonant have to be discribed by another character without initial consonant, like 易，羊益切 ([ʝ-]and [-i] becomes [ʝi]).
It would have been an ideal constellation if the characters to be used for the fanqie transcription would have been standardized. Yet this is not the fact. The characters used to describe the pronunciation of the character 冬 vary from dictionary to dictionary, and all characters with the initial sound of [d] or the final sound of [-ʊŋ˥˩] could be used, as long as the pronunciation was identical with that of the character 冬. Scholars therefore adhere to a short number of traditional dictionaries to indicate the pronunciation, like the Guangyun 廣韻 from the Tang period 唐 (618-907) and the Jiyun 集韻 from the Song period. Inside these dictionaries, the fanqie system is quite coherent, so that for the same initial sounds and for the same finals, always the same character is used.
|冬||都宗切||t(u˥˩) + (ts)uoŋ˥˩||t + uoŋ˥˩ =||tuoŋ˥˩||(d+ong=) dōng|
|舉||居許切||k(ĭo˥˩) + (x)ĭo˥||k + ĭo˥ =||kĭo˥||(j+u=) jǔ|
|去||羌舉切||kʰ(ĭaŋ˥˩) + (k)ĭo˥||kʰ + ĭo˥ =||kʰĭo˥||(q+u=) qù|
|野||承與切||ʑ(ĭəŋ˩) + (j)ĭo˥||ʑ + ĭo˥ =||ʑĭo˥||(y+e=) yě|
|撫||芳武切||pʰ(ĭwaŋ˥˩) + (m)ĭu˥||pʰ + ĭu˥ =||pʰĭu˥||(f+u=) fǔ|
|易||以豉切||j(ĭə˥) + (ʑ)ĭe˩˥||j + ĭe˩˥ =||jĭe˩˥||(y+i=) yì|
|玉||魚欲切||ŋ(ĭo˩) + (j)ĭwok||ŋ + ĭwok =||ŋĭwok||(y+u=) yù|
Columns from left to right: character, fanqie description, transcription of reconstructed sounds, explanation, result, modern pinyin transcription.
A matter complicating the fanqie system is that the pronunciation changed over time and from place to place, so that it was never possible to establish a standard pronuncation valid in the whole of China and over more than a century or so.
The system is highly valuable for the reconstruction of the original pronunciation of characters in Middle Chinese or Early Modern Chinese, but it can often not be understood if using the modern Mandarin pronunciation or the tone pitches of modern Chinese, because they differ from the Middle or Early Modern pronunciation, as in the instances 刊[kān] (level pitch), 苦寒[-án]切 (rising pitch); 權[tɕʰyɛn] (aspirated), 巨[dʝ-]員切 (non-aspirated); 祕[bi],兵媚[-eɪ̯]切 (different final sound); or 任[ʐən],如林[-in]切 (different final sound).
A standardization of the fanqie system was only realized during the Ming and Qing periods, by scholars like Lü Kun 呂坤 ((1536-1618), author of Jiaotaiyun 交泰韻, Yang Xuanqi 楊選杞, author of Shengyun tongran ji 聲韻同然集, Pan Lei 潘耒 (1646-1708), who wrote the book Leiyin 類音, Li Guangdi 李光地 (1642-1718), or Wang Lansheng 王蘭生, author of Yinyun chanwei 音韻闡微, as well as Liu Xizai, who complied the handbook Sisheng dingqie 四聲定切. They established rules for the use of characters to indicate initial and final sound. Around 1900, a series of alphabets (the qieyin 切音 alphabets) was invented which were more convenient than the traditional system of rhyme groups.