Different pronunciations of "she's" depending on the meaning

Question

According to The Oxford Advanced Learner's Dictionary, the contraction she's may be pronounced both with a short [i] sound(as in pit) and a long [i:] sound(as in sheep) when it means she is, but it must be pronounced with a long [i:] sound when it means she has.

I've always thought that she's is pronounced with a long [i:] only when it's used emphatically, regardless of its meaning. For example,

1.She's not coming with us. (she is, [i])
2.She's been doing well. (she has, [i])
3.She's the one who stole your keys. (she is, emphatic, [i:])
4.I don't have your keys. She's got them. (she has, emphatic, [i:])

According to the dictionary, however, I am wrong at least in my example 2. English is only my third language, so maybe I don't distinguish between [i] and [i:] as well as I should, but I hear the word she's in examples 1. and 2. pronounced in exactly the same way.

Questions for native speakers:

• Were you aware of this difference in pronunciations of she's?
• If I(or anyone else) were to pronounce she's from example 2. with a short [i], would you actually sense that something was pronounced not quite as it should have been?
• Would you pronounce she's with a long [i:] in a non-emphatic context?

Answer 1

Not all English dialects distinguish between the HAPPY vowel [i] and the FLEECE vowel [iː]; for example, General American does not.

One distinction that is made in all English dialects is the tense/lax distinction: the FLEECE vowel, tense [iː] vs the KIT vowel, lax [ɪ].

Note the terminology of tense vs lax, not long vs short. This is not just a length distinction, but a quality distinction. The tense vowel tends to be longer, higher, and sometimes becomes diphthongized.

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EDIT: I realized I only answered part of your question.

She's < she is and she's < she has are homophones in all dialects. There is no difference in pronunciation based on the meaning of the contraction.

Answer 2

This might be true of British speech -- I wouldn't know -- but it's certainly not true for American speech, where she's can be pronounced anywhere from /ʃiz/ to /'ʃijəz/, with tense /i/ in all cases.

And where all of these she's-es can represent either she is or she has. It's totally ambiguous.

Exactly like she'd (/ʃid/ to /'ʃijəd/), which can represent either she had or she would. Contractions contract information; what's lost can be regained from context. And ambiguity is not a bug; it's a design feature.

Answer 3

As a native English speaker, I would hear she's in #1 and #2 exactly the same way too. In fact, I can imagine #3 pronounced as [i], depending on the individual speaker.

Answer 4

I do hear a difference (in British and Australian English, the versions of English I predominately speak) when I read the sentences to themselves. But if you swap the vowel sounds, I'm pretty sure you'll still be well understood as the meaning is clear in context.