-uan pinyin pronunciation

Question

It seems to me that in Mandarin, two different vowel sounds are used for words whose pinyin ends with -uan.

In some words, like 全 (quán) and 元 (yuán), the vowel sounds like "oo-en" (the nucleus/coda are "ɛn" in IPA, rhymes with English "hen").

In other words, like 換/换 (huàn) and 亂/乱 (luàn), the vowel sounds like "oo-an" (the nucleus/coda are "an" in IPA, rhymes with Mandarin "安").

Does this difference really exist, or an I imagining it? If there is a distinction, what's the rule for which pronunciation to use? It seems related to the tone and the initial consonant, but I'm not sure there is a definite pattern.

Answer 1

There are several cases in Mandarin of multiple sounds sharing the same symbols in Pinyin, such as -uan as you've noticed, as well as -i which has multiple sounds associated with it. In the case of -uan, this final behaves differently when prefaced with the initials y-, j-, q-, and x-. As a general rule, -u, -ue, -uan, and -un behave differently when prefaced with those 4 initials and you'll see them separated out on any pinyin chart:

The u in these cases is actually a ü which does not exist in English and is something I struggle with myself so I'll just redirect you here.

Answer 2

When ü is used in zero initial syllables, use yu instead:

• ü → yu (鱼)
• üe → yue (月)
• üan → yuan (元)
• ün → yun (云)

You should read these yu as ü.

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When ü is used with j, q, x, use u instead:

• ü → ju (巨), qu (去), xu (许)
• üe → jue (绝), que (却), xue (学)
• üan → juan (卷), quan (全), xuan (选)
• ün → jun (军), qun (群), xun (寻)

You should read these u as ü.

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In all other cases, use ü as is:

• nü (女), lü (绿), nüe (疟), lüe (略)

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In your example, u in huan, luan are different from u in quan, juan. First ones read as u, the second ones read as ü actually. And yuan reads as üan.