Pronunciation Rule for "nt" in the Middle of Words

Is there a "rule" or pattern for the pronunciation of "nt" in the middle of words, followed by a vowel (or "er" sound)?

Here's what I have so far:

1) "t" is often omitted in words like "wanted," "mental," and "international" when "nt" is followed by a vowel or an "er" sound.

2) If the syllable following the "nt" is stressed, the "t" is pronounced: "integrity," "intoxicated," and "intact"

3) In words with "int," the "t" is sometimes obligatory, such as in "interrogation" and "interpretation," BUT it is not obligatory in others like "interception." The only pattern I see so far is that when the root word has a stressed syllable following the "nt," this carries over into the longer forms of the word. For example, "inTERRogate" is pronounced with a "t" and "interrogation" is also pronounced with a "t" (even though the syllable following the "nt" is no longer stressed).

4) In words like "attention," the "ti" is pronounced as /ʃ/ ("sh").

Can anyone think of additional examples or rules? Are there any examples which would contradict my reasoning so far?

Solution 1:

When it comes to nt reduction to n in American English that results in winter and winner being pronounced the same, there is an entry in J. C. Wells' blog about it:

http://phonetic-blog.blogspot.com/2011/11/winter-and-winner.html

Here are the most relevant extracts:

• The environments in which nt-reduction operates seem to be the same as those for t-voicing. In particular, it does not happen in the environment of a following stressed vowel, as in intend, contain, nor of a following unstressed but strong vowel as in intake; nor does it apply to ntr clusters, as in country. The t can be lost in centre/center but not in central.
• Some words may be special cases, In particular, I have the impression that ninety in AmE is often ˈnaɪndi rather than the expected ˈnaɪnti or ˈnaɪni. Does the same apply to seventy? Are there other exceptional cases?

There is also the case of nt followed by an n sound as in Clinton. In Clinton, nt often reduces to /n/ followed by a glottal stop /ʔ/: /ˈklɪ̃nʔn̩/, and not /ˈklɪntən/ which remains possible.