So time for an update…
If you want to play by the books, biang
is not a permissible syllable. If you are concerned with what comes out of a speaker’s mouth, syllables like nim
(contraction of 你們) are even possible, although they are technically surface realizations of a phonology that does not allow such syllables.
The surprising fact is that iang
as a rime for the labial initials (b
, p
, ph
, m
) did not even exist in Middle Chinese, so the omission of biang
is nothing new. That isn’t to say it couldn’t develop in Mandarin, but there was nothing shaping the language in that direction. The only likely source would be a borrowing sort of like how fiao
is a borrowing from Wu, which has its own interesting story.
Old Answer
I’ve made a chart here for my own understanding of Standard Mandarin Chinese phonology a while ago:
a ai au an aŋ e ə əi əu ən əŋ i ia iai iau ian iaŋ ie iə iəu iən iəŋ io iu iuan iuə iun iuəŋ aɻ o u ua uai uan uaŋ uə uəi uən uəŋ m n ŋ
a ai ao an ang ê e ei ou en eng yi ya yai yao yan yang yê ye you yin ying yo yu yuan yue yun yong er o wu wa wai wan wang wo wei wun weng m n ng
p ba bai bao ban bang bei ben beng bi biao bian biang bie biu bin bing bo bu
pʰ pa pai pao pan pang pei pou pen peng pi piao pian pie piu pin ping po pu
m ma mai mao man mang me mei mou men meng mi miao mian mie miu min ming mo mu
f fa fan fang fei fou fen feng fiao fo fu
t da dai dao dan dang de dei dou den deng di diao dian die diu ding du duan duo dui dun dong
tʰ ta tai tao tan tang te tou teng ti tiao tian tie tiu ting tu tuan tuo tui tun tong
n na nai nao nan nang ne nei nou nen neng ni niao nian niang nie niu nin ning nü nüe nu nuan nuo nong
l la lai lao lan lang le lei lou leng li lia liao lian liang lie liu lin ling lü lüe lo lu luan luo lun long
ts za zai zao zan zang ze zei zou zen zeng zi zu zuan zuo zui zun zong
tsʰ ca cai cao can cang ce cou cen ceng ci cu cuan cuo cui cun cong
s sa sai sao san sang se sou sen seng si su suan suo sui sun song
tʂ zha zhai zhao zhan zhang zhe zhei zhou zhen zheng zhi zhu zhua zhuai zhuan zhuang zhuo zhui zhun zhong
tʂʰ cha chai chao chan chang che chou chen cheng chi chu chua chuai chuan chuang chuo chui chun chong
ʂ sha shai shao shan shang she shei shou shen sheng shi shu shua shuai shuan shuang shuo shui shun
ɻ rao ran rang re rou ren reng ri ru rua ruan ruo rui run rong
tɕ ji jia jiao jian jiang jie jiu jin jing ju juan jue jun jiong
tɕʰ qi qia qiao qian qiang qie qiu qin qing qu quan que qun qiong
ɕ xi xia xiao xian xiang xie xiu xin xing xu xuan xue xun xiong
k ga gai gao gan gang ge gei gou gen geng gu gua guai guan guang guo gui gun gong
kʰ ka kai kao kan kang ke kei kou ken keng ku kua kuai kuan kuang kuo kui kun kong
x ha hai hao han hang he hei hou hen heng hu hua huai huan huang huo hui hun hong
The table contains every possible pinyin in Standard Mandarin Chinese sans tones. Columns are headed by the finals, and rows are headed by the initials. They are derived from the Standard Chinese phonology and Pinyin table pages on Wikipedia. A quick look at the table will reveal patterns in the phonology with a few oddities.
biang
is certainly listed in the Pinyin table, but a quick search for any word with a pinyin of biang
produces 0 results. And it makes sense: because the bilabial/labiodental series of initials (b-, p-, m-, f-) is excluded from combining with many finals (such as: -uan, -uo, -ui, -un, -ong). Have a look at the iaŋ column and you see that piang
, miang
, and fiang
are missing; biang
looks like it should not be there either.
Yes, there are oddities where a sound that looks like it should be there isn’t there (like bou
, tei
, and ten
), but they can be easily explained as, “there weren’t any words that used that sound.” It’s what is called an “accidental gap,” and you can read more about it here: Phonotactics (âm pháp). It’s much more difficult to make a case for biang
which exists in no dictionaries, is not in common usage, and is the sole proprietor of the Pinyin “biang.” Considering the facts, it’s my opinion that biang
is illegal in Standard Mandarin Chinese phonology and was probably concocted for promotional purposes. What better way to stand out than to own a “rare” character, a “rare” sound, and an exclusive position in the Pinyin table?