Sandhi(sound changes)

[soekothu]

Hi,
pls,let me know about the following sound changes.And i want to know the grammatical or phonological rules if there are.

eg,teach want we
teaches(plural) wanted(past) we're(abbreviation)
For instance, let me know voice or voiceless,aspirated or unaspirated.

[xpert]

teaches (plural) /ch/ voiceless
If a word ends with /s/, /z/, /sh/, /ch/-chair, /zh/-the second "g" in garage, /dz/-(j), pronounce "s" or "-es" as /iz/. /iz/ is an additional syllable.


wanted(past) /t/ voiceless /d/ voiced
If a verb (mostly regular) ends in /t/, /d/ you add one more syllable /id/


we're (abbreviation) .. This is a contracted (spoken) form of we are.