What Are Alternants? A Quick Linguistics Guide

 

In English, some morphemes change pronunciation depending on the final sound of the word they attach to. Alternants are simply different pronunciation forms that a single linguistic unit- like a morpheme – can take. Alternants are allophones when talking about sounds, and allomorphs when talking about morphemes, but the general word for different versions is alternants. For example:

In English, the plural -s (same spelling) has different phonetic forms depending on the final sound of the noun:

Noun Ends With	Plural Ending Pronouned as	Example	Ipa
Voiceless sound (e.g. /p/, /t/, /k/)	/s/	cat → cats	/kæts
Voiced sound (e.g. /b/, /g/, vowel)	/z/	dog → dogs	/dɔːgz/
Sibilant sound (e.g. /s/, /z/, /ʃ/, /ʒ/, /tʃ/, /dʒ/)	/ɪz/ or /əz/	bus → buses	ˈbʌsɪz/

 So the same-s is pronounced /s/, /z/, or /ɪz/ depending on context — a clear example of phonetic alternation. If the preceding sound is /s/, it often triggers an /iz/ or /ez/ alternant because two /s/- like sounds in a row are hard to pronounce.

Here, /s/, /z/, and /əz/or/Iz/ are alternants of the plural morpheme -s in English. Thus, we see that /s/ after /p, t, k, f, θ/ as in 'ships' / ʃips/, 'cats' /kæts/ etc.  

/z/ after vowels and /b, d, g, v, ð, m, n, l, ŋ/ as in dogs /dɔːgz/,pens /penz/, sings /siηz/, and so forth.      

 /ız/ after /s, z,ʃ,tʃ,ʤ / as in praises /preizız /, catches/ kætʃΙs/, etc.      

Similar situation emerge from the past tense morpheme -ed as /t/, /d/  and /Id/.

bloomfield calls this sort of alternants 'phonetic alternants' as they can be described in terms of phonetic modification. however,later linguists employ the term 'allomorph' to designate the alternants.

This particular kind of alternation, moreover, is described by the later linguists as 'phonologically determined alternation' since the phonological characteristics of the environment determine it.  Furthermore, even agglutinative languages possess 'phonetic modification', for instance, in Swahili, 'm (him) is replaced by 'mw' before vowels:

a - li -m - penda 'he loved him'.

a - li - mw-ona   'he saw him'.

Irregular Alternants

Bloomfield puts forward 'irregular alternants' which, when added to roots of words/syllables, change the final consonants of the roots, that is, in singular final consonants being voiceless whereas in plural voiced:

knife/ naıf/  knives /naıvz /,

house/ haus/   houses/ hauzız/, etc.

The phonetic environment conditions these alternants. However, this phenomenon is not generally applicable, for example, to cliffs, myths, and so on.