Students understanding the complexity of language

Chapter 11.8: Assimilation


chapter 11.8: Assimilation

The principle of least effort, also called ease of articulation, describes how speakers of a language naturally seek to expend the least effort possible to articulate sounds without losing intelligibility. Illustrations of this can be seen in many of the allophones that exist, such as the two types of /k/ in the words leak and lock. Because of the front vowel in leak, it requires less effort to keep the tongue nearer to the front of the mouth to produce the following /k/, resulting in a fronted, or palatalized [k’]. This change of one sound to become more like another that is near to it is called assimilation. We have three types of assimilation to discuss for consonants:

  1. assimilation of place, where a consonant changes its place of articulation
  2. assimilation of manner, where a consonant changes its manner of articulation
  3. assimilation of voicing, where a consonant changes whether or not it is voiced.

Assimilation of place

The example above, where the /k/ moved toward the front of the mouth, is an example of assimilation of place. Assimilation of place is very common in English, especially with the three nasal phonemes. For example, the phoneme /n/ in the word pan is a voiced alveolar nasal, but when it is joined to form the word pancake, many people pronounce the /n/ now as a velar nasal, that is [ŋ], because it has assimilated to the following velar sound of the [k] in cake: [pæŋkek]. The same assimilation of place with [n] becoming [ŋ] in words like incredible or ink.

Another nasal assimilation of place occurs in words like symphony, where the bilabial [m] is followed by a labiodental fricative [f]. This word is often pronounced with a labiodental nasal, represented by the symbol [ɱ]: [sɪɱfəni].

Another very common type of assimilation of place is called palatalization, which means that sounds are moved towards the palate. The example above of the [k’] in leak is an example of a velar sound being pulled towards the palate by the front vowel. This same processed is the origin of the palatal phoneme /tʃ/ in English, a sound developed in early Old English from by palatalizing /k/. Many phonemes were also palatalized in the early Modern English period when the vowel /u/ in some words developed a palatal semivowel glide before it, causing [u] to become [ju]. When this palatal sound [j] came after the alveolar sounds /s/, /z/, /t/, /d/, it pulled them back to the palate, creating the following new pronunciations (in linguistics, the symbol > means “becomes,” as if it were an arrow, pointing to the new creation):

  • [sj] > [ʃ]: sure, sugar
  • [zj] > [ʒ]: pleasure, measure
  • [tj] > [tʃ]: nature, creature
  • [dj] > [dʒ]: educate,adulate

The spelling of these words, which was set before the phonological change, reveals how these words would have been pronounced in Shakespeare’s day: sure and sugar were pronounced with [s], pleasure and measure were pronounced with [z], and nature and creature were pronounced with [t]. Furthermore, the <u> was pronounced [u], not [ju]. (As an aside here, the development of [u] to [ju] is an unconditioned change and although its development is common throughout Modern English, it did not develop for all speakers. There are still speakers of English who pronounce words like pleasure with a [z] and have no [j] before the [u]. In American English there is a divide between people who pronounce words like news or tune with a straight [u] and those who pronounce them with [ju]).

If we concentrate on Present-Day English, we see the effects of palatalization ongoing, not only within individual words like discussed above, but in word boundaries. For example, when a word that ends in the alveolar [t], like don’t is followed by a word that begins with [j], as in the phrase don’t you, then for many speakers the [t] is palatalized in the same way as above to become [tʃ]. This also happens with words than end in [s] and [d]:

  • [sj] > [ʃ] “Bless you” pronounced [blɛʃ ju] (“Blesh you”)
  • [tj] > [tʃ] “Don’t you” pronounced [dontʃ ju] (“Donchu”)
  • [dj] > [dʒ] “Did you” pronounced [dɪdʒ ju] (“Didge you”)

Assimilation of Manner

In addition to allophones changing their place of articulation through assimilation, some change their manner of articulation. This is a much rarer type of assimilation, but it does occur. Examples may be found in phrases like “good night,” where the final alveolar plosive [d] of “good” becomes an alveolar nasal [n]: [ɡʊn naɪt].

Assimilation of Voice

In this type of assimilation, a voiceless sound that is near a voiced sound will become voiced, or a voiced sound that is near a voiceless sound becomes voiceless. This type of assimilation is incredibly common in English. For example, the precise form of the plural ending –s will be the voiceless [s] if the word ends in a voiceless sound, but [z] if the word ends with a voiced sound: back makes a plural with [s] to produce [bæks], while bag makes a plural by adding [z], to produce [bægz].

The same process occurs with the past tense ending –ed. It remains voiced in words that end with a voiced consonant, like joined [dʒɔɪnd], but in words that end with a voiceless sound, it assimilated to the voiceless [t], as in jumped [dʒʌmpt].

Using characteristic features to show assimilation

It is easier to understand exactly how assimilation works by considering the characteristic features of the sounds affected:

1. The assimilation of place of [n] to [ŋ] in “pancake” can also be written as

[n] [ŋ]
[+alveolar] [+velar]
[+nasal] –> [+nasal]
[+voice] [+voice]

Of the three features of [n], the only one that changes is the one describing the place, which moves from [+alveolar] to [+nasal].

2. The assimilation of manner in [d] to [n] in “good night” can be written as:

[d] [n]
[+alveolar] [+alveolar]
[+plosive] –> [+nasal]
[+voice] [+voice]

3. The assimilation of voicing in [s] to [z] in “bags”:

[s] [z]
[+alveolar] [+alveolar]
[+fricative] –> [+fricative]
[-voice] [+voice]

With the example of the past tense jumped, we have:

[d] [t]
[+alveolar] [+alveolar]
[+plosive] –> [+plosive]
[+voice] [-voice]

Other types of sound changes


The opposite of assimilation is dissimilation, when sounds become less alike. Although it might seem paradoxical, this is also a function of the principle of least effort: sometimes it is difficult to say two very similar sounds in a row. This often happens with /r/ and /l/ as can be seen in our word pilgrim which is derived from Latin peregrinus. Because the two instances of [r] so near each other are difficult to say (especially in a time when /r/ was pronounced as [r] or as the alveolar flap [ɾ]), the first one changed to [l]. To express it through features:

[r] [l]
[+alveolar] [+alveolar]
[+central] –> [-central]
[-lateral] –> [+lateral]
[+approximant] –> [+approximant]
[+voice] [-voice]

Another one that you may have heard in some dialects is “chimley” for “chimney,” where the two nasals so close together caused one to change to an approximant. More common is the change where an alveolar stop [t] that occurs before an alveolar nasal [n], as in the words kitten, beaten dissimulates to become a glottal stop [ʔ]:

[t] [ʔ]
[+alveolar] [+glottal]
[+plosive] –> [+plosive]
[-voice] [-voice]


Another result of the principle of least effort is simplification. This change does not involve a change in features but rather the loss of a segment when consonants occur in groups of two or more. For example, the word hand, pronounced [hænd], ends in two consonants, but when plural ends in three, [hændz]. Three consonants in English will often be simplified to two, resulting in the pronunciation [hænz]. Two consonants can also simplify to one (for example, many people do not pronounce the final [d] of “hand”: [hæn]).


Another common consonant change does not involve a change of features or the loss of a segment but instead the reversal of order of the phonemes. This is metathesis: the reversal of two sounds. Common ones today usually involve the phoneme /r/. For example, in the word iron, the spelling reveals that the word used to be pronounced with the [ɹ] before the vowel, while now we pronounce it after the vowel. The same is true of the word third, where the word three shows the original order of the [ɹ] and the vowel. These two examples are accepted as standard English pronunciations, but most of us are aware of non-standard examples as well, such as “purty” for pretty.

Examples of metathesis with sounds other than [ɹ] are less common today, but one that occurs frequently is “aks” for ask. This pronunciation often has negative associations in American English which is ironic since “aks” was the more common form in the Old and Middle English periods, used by both King Alfred and Chaucer. It can still be found in non-standard dialects throughout England.