/kʊdnt/ → /kʊbm/, /wʊdnt/ → /wʊbm/, etc.
The assimilated new phoneme can produce a domino effect which triggers further processes of assimilation. This gives rise to very interesting cases, not at all infrequent.
Have a look at this example:
Now follow the different stages of the process:
- First, the /t/ dissapears, which can happen because of elision or just because the /t/ is frequently dropped in negative contractions.
- Then the /n/ becomes a /m/because, now we no longer have a /t/, it is followed by a bilabial /b/.
- Finally, the /d/ is turned into a /b/ because now the next sound is a bilabial /m/.
- So, /kʊdnt/ becomes /kʊbm/.
And here there are some examples from real life:
My take on this is that, had the potato not failed again in the summer of 1846, we wouldn’t be here talking about the famine at all | wʊdm bi ˈhɪə | The /d/ is not assimilated in this case (Cormac Ó Gráda, BBC4; notice that he’s an Irish speaker of English).
Now have a look at these examples where the /d/ is dropped because of elision and then the /n/ is assimilated into /m/. As you can see, in the first case the assimilation takes place at word boundaries whereas in the second case it occurs within a single word.
OK, it can happen that someone reads a line with a different inflection or emphasis and then I find myself changing my reading because he’s changed his. | faɪm maɪˈself | (Cambridge Proficiency test).
“Temporal landmarks help stop the feeling that time’s whizzing by. I bet, for example, you retain memories of events that happen near the beginning or end of term – they’re kind of landmarks – better than those that happened somewhere in between”. “So?” “So establish a few landmarks – remember to mark special events like birthdays properly with some sort of celebration. Notice how the speaker pronounces /ˈlæmmɑːk/ (Cambridge Advanced test).