SLTinfo logo


go to contents icon

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.

comfort /kʌmfət/ [k̠ʰʌ̃ɱfətʰ]

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

labialization process 1

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.

home visit /həʊm vɪzɪt/ [həʊ̃ːɱvɪzɪtʰ]
born free /bɔn fri/ [bɔ̃ːɱfɹ̥ɪ]

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.

ring fence /rɪŋ fɛns/ [ɹɪ̃ɱ fɛ̃ns]

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.

labialization process 2

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.

life peer /laɪf pɪə/ [laɪɸ pʰɪəː]
live band /laɪv bænd/ [laɪːβ bæ̃nd̥]

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.

NEXT>> De-voicing of Liquids