Coarticulation in phonetics refers to two different phenomena:
the assimilation of the place of articulation of one speech sound to that of an adjacent speech sound. For example, while the sound /n/ of English normally has an alveolar place of articulation, in the word tenth it is pronounced with a dental place of articulation because the following sound, /θ/, is dental.
Crowley, Terry. (1997) An Introduction to Historical Linguistics. 3rd edition. Oxford University Press.
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