In order to comprehend the mechanisms of assimilation some comprehension of the production of speech sounds is needed: Roach, P., English Phonetics and Phonology (4th ed.), Cambridge, CUP, 2010, is recommended.

The most common form involves the movement of place of articulation of the alveolar stops /t/, /d/ and /n/ to a position closer to that of the following sound. For instance, in the phrase ten cars, the /n/ will usually be articulated in a velar position, /ˈteŋ ˈkɑːz/ so that the organs of speech are ready to produce the following velar sound /k/. Similarly, in ten boys the /n/ will be produced in a bilabial position, /ˈtem ˈbɔɪz/ to prepare for the articulation of the bilabial /b/.