So, we don't change /t/ to /d/ if /t/ is between 2 vowel sounds and /t/ is the beginning of the stressed sound in a word in American English, right? [duplicate]

Ok, see this word entertainment has IPA of /en.təˈteɪn.mənt/. Ok, now in American English if /t/ is between 2 vowel sounds then it will become /d/ cos it is flap T.

But /t/ will become flap T only if the sound in the word is not stressed. Is that correct?

For example, for the above example, we can pronounce /en.dəˈteɪn.mənt/ but not /en.dəˈdeɪn.mənt/, right?

Solution 1:

t/d/n become flaps when they are (1) after a vowel or glide (including r but not l), (2) before a vowel, and (3) at the end of a syllable. (Condition (3) is stated with the assumption that an intervocalic consonant before an unstressed vowel goes at the end of the preceding syllable.)

"Entertainment" has a rather involved derivation. After nasalizing the preceding vowel, the first n is lost by a rule that deletes nasal consonants before voiceless consonants at the same place of articulation. The first t is now between vowels and at the end of a syllable, so it flaps. The flap assimilates in voice to the preceding and following voiced vowels, and being a sonorant consonant, it also assimilates in nasality to the preceding nasal vowel, so we wind up with a nasal voiced flap between the first two vowels of "entertainment". Nothing remarkable happens in the "tainment" part of the word, except [n] optionally assimilates in position to following [m].

This follows the phonological treatment worked out a long time ago by my teacher David Stampe. Note that there is never a d at any stage of the derivation, and there is never an intervocalic n, either.

[ɛ̃ɾ̃ɹ̩̃tʰej̃mmə̃nt̚]

Solution 2:

As an American, I would say I pronounce the word quite differently than your rendition:

en'-ter-teɪn'-ment

With both "t" sounds. However, please note, neither is actually between two vowel sounds. A better example would be letter.

led'-er