Allophonic assimilation – labialization

Within words, we have seen elsewhere that whenever the bilabial nasal /m/ or the alveolar nasal /n/ appears before a labiodental fricative /f, v/ they are likely to assimilate the labiodental place of articulation, e.g.

A similar process of allophonic assimilation can also across a word boundary. This pattern is summarized in the following rule.

This is read as:

‘If the sound in word-final position of the word preceding the word boundary is a nasal /m, n, ŋ/ and if the sound in word-initial position in the word immediately following the word boundary is a labiodental  fricative /f, v/ then the nasal is labialized.’

Examples of this rule in operation include the following.

The assimilation of a bilabial or alveolar nasal before a labiodental fricative is reasonably common in connected speech. The assimilation of the velar nasal to a labiodental nasal in this context is, perhaps, less common but it is still possible to find examples in rapidly articulated speech, e.g.

We can, therefore, summarize this rule with the following statement.

Word-final nasals are labialized before labiodental fricatives.

Another type of labialization occurs when labiodental fricatives occur in word-final position before a bilabial plosive, i.e.

The IPA symbol [ɸ] is used to represent the voiceless bilabial fricative, and [β] to represent the voiced bilabial fricative. These two phones have no contrastive function in English and they are, therefore, allophones of the corresponding phonemes /f/ and /v/. Examples of this process in action include the following.

Interestingly, this process does not occur within words in English but only across word boundaries in rapidly articulated connected speech. We can state this rule as follows.

Word-final labiodental fricatives are labialized before bilabial plosives.

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