Pronunciation of "undoable"

Question

As this question points out, there are two different meanings of undoable.

I can't find any phonetics how they are pronounced. I guess that the difference is barely audible. Or do you stress the word so that it is capable of being differentiated?

I found phonetics for undo and doable^{(copied from OALD)}

• undo: ʌnˈduː
• doable: ˈduːəbl

It would be logical that both undo-able and un-doable are pronounced equal.

• ʌnˈduː has a trailed əbl
• ˈduːəbl has a precedent ʌn.

Both leads to: ʌnˈduːəbl.

But I conjecture this pronunciation to differentiate them:

• un-doable: ʌnˈduːəbl
• undo-able: ˈʌnduːəbl

Is there any audible difference in pronunciation? Perhaps are there also any difference between British and American English?

Answer 1

• your pronunciation of 'doable' looks correct (for AmE)
• the phonemes you have for 'undo' look correct, but the stress pattern, though formally correct may not allow you to draw inferences about changes well. It is more a word with two stressed syllables (a 'spondee')
• adding on affixes is not independent in English. You have to take in to account the whole word to get it right.
• so the correct pronunciation is your first one ʌnˈduːəbl

As an aside, the schwa in English (or GenAmE, I can't speak for others) is always in an unstressed position, and the 'ʌ' is almost a schwa.