Assimilation (phonology)

In phonology, assimilation is a sound change where some phonemes (typically consonants or vowels) change to be more similar to other nearby sounds. It is a common type of phonological process across languages. Assimilation can occur either within a word or between words. It occurs in normal speech, and it becomes more common in more rapid speech. In some cases, assimilation causes sound spoken to differ from the normal 'correct' pronunciation of each sound in isolation. In other cases, the changed sound is considered canonical for that word or phrase. For an English example, 'handbag' (canonically /ˈhændˌbæɡ/) is often pronounced /ˈhæmbæɡ/ in rapid speech. This is because the and sounds are both bilabial consonants and their places of articulation are similar; whereas the sequence - has different places but similar manner of articulation (voiced stop) and is sometimes elided, causing the canonical phoneme to sometimes assimilate to before the . The pronunciations /ˈhæn.bæɡ/ or /ˈhænd.bæɡ/ are, however, common in normal speech. By contrast, the word 'cupboard', historically a compound of 'cup' /kʌp/ and 'board' /bɔːrd/, is always pronounced /ˈkʌbərd/ and never */ˈkʌpbɔːrd/, even in slow, highly articulated speech. As in these examples, sound segments typically assimilate to a following sound, but they may also assimilate to a preceding one. While assimilation most commonly occurs between immediately adjacent sounds, it may occur between sounds separated by others. Assimilation can be synchronic—that is, an active process in a language at a given point in time—or diachronic—that is, a historical sound change. A related process is coarticulation, where one segment influences another to produce an allophonic variation, such as vowels becoming nasalized before nasal consonants (/n, m, ŋ/) when the soft palate (velum) opens prematurely or /b/ becoming labialized as in 'boot' or 'ball' in some accents. This article describes both processes under the term assimilation.