Alternation

Try reading the following sentence out loud and see how many versions of the indefinite article "a" you hear:

I bought a great book, so maybe I can take a break from studying for an exam.

Did you notice that "a" sometimes sounds like "ay" (/eɪ/) and other times like "uh" (/ə/)? And then there's "an" before the word "exam." Alternation is responsible for the different versions of the indefinite article "a." This little experiment was an example of phonological alternation, which means alternating sounds based on the other sounds in the word.

Alternation Definition

Before we dig into the different types of alternation, let's begin with the definition of alternation itself.

A variant form of a word in the process of alternation is called an alternant. For example, the various forms of the indefinite article "a"— /eɪ/ and /ə/—are each a variant.

An example of alternation is seen in how the word "thief" ends with the voiceless fricative /f/ (i.e., the sound made by forcing air through the teeth), but this changes when we want to pluralize the word. The fricative /f/ changes to the voiced sound /v/, and "thieves" becomes the appropriate alternant.

So, the /f/ alternates to a /v/ because of the addition of the /s/ to the word thief. The important thing to remember is that two (or more) alternants represent a single unit of meaning, called a morpheme. The production of the morpheme may change with alternation—i.e., it will change from /f/ to /v/—but the basic meaning of the word does not. In other words, we're simply talking about multiple thieves instead of one thief; the root of the word is the same.

For example, the article “a” is realized (which means produced from an abstract linguistic concept) differently in a variety of contexts; it might be pronounced /ə/ or /eɪ/ depending on the situation. Alternation never changes the meaning, only the way the word is pronounced or, in some cases, spelled.

Fig. 1 - The IPA contains a character to represent each speech sound, which has helped standardize written linguistic data and reduce confusion.

Alternation is not specific to just English, and it’s seen across many languages, which is why it’s widely studied in linguistics.

Alternation in Linguistics

You may also hear alternation in linguistics referred to as morphological alternation because it is a subfield of morphology.

When two sounds alternate in the same word or word stem, depending on the context, there must be a restriction on the distribution of a phonological rule that doesn’t apply to the other.

As an example, the word meat is pronounced /mit/, with the consonant /t/ at the end, but the word meaty is pronounced /miɾi/ where the /t/ is replaced with a quick flap /ɾ/.

This means that the voiceless /t/ is switched for the voiced /ɾ/. This change is due to the fact that the letter “t” is placed between a stressed and unstressed vowel (other examples include butter and wedding).

Alternation often occurs to make something easier to pronounce. In this instance, the /ɾ/ sound will be easier to pronounce by reducing the amount of time to pause for the /t/ sound.

There are specific conditions that can trigger an alternation to occur. The realization of the alternant may be due to its phonological, morphological, or lexical environment - let's learn more about these processes now.

Phonological Alternation

Phonological alternation is where the surrounding sound structure creates the conditions for the alternants. The “flapping” of the /ɾ/ sound in the word meaty is an example of the sounds creating an environment where alternation might take place.

Look at the following word pairs for another example of phonologically conditioned alternation:

Notice that despite the affix (-s) remaining the same among the three words, each takes a different alternant to represent the sound of the letter "s." Each requires the "s" to take a distinct spoken form that matches whether the previous phoneme is voiced or voiceless. Because /t/ is voiceless, it takes the voiceless alternant /s/, and because /g/ is voiced, it takes the voiced /z/ alternant.

Fig. 2 - Vocal cords vibrate much like a plucked guitar string when air is pressed from the lungs through the throat to create a "voiced" sound.

Morphological Alternation

Morphological alternation is where the choice of alternants depends on the morphological context.

The words bat, bag, and house all took the affix "-s" to make them plural, but each presented differing phonemes to represent the "-s" due to the surrounding phonemes in the words. Similarly, some words, when pluralized, exhibit morphologically conditioned alternants.

These words are unlike other nouns that typically receive the suffix -s to make them plural. Oxen is an alternant of ox, and so on.

Lexical Alternation

Lexical alternation is where the choice of alternants depends on a particular lexeme, which is essentially the basic form of a word with zero inflection. These are cases where neither the phonological nor the morphological surroundings can help, so the choice of alternants can't be derived by rules. Lexical alternation requires the memorization of alternants.

Alternation Example Outside of English

The rule is:

• if the last vowel in the word is a, ı, o, or u: use the /lɑr/ form
• if the last vowel in the word is e, i, ö, or ü: use the /lɛr/ form

Notice that the final vowel in the words that took the /lɛr/ altnernant was i and ö, while the final vowel in the words that took the /lɑr/ alternant was a and o. This is in keeping with the rule of major vowel harmony.

Alternation vs. Alteration

A quick word here about the difference between alternation and alteration, as these words are easily confused with one another. If you happen to forget the 'n' in the middle of the word alternation and accidentally spell alteration, you will not be discussing a different linguistic phenomenon—alteration is not the name of a specific linguistic event like alternation.

Alteration simply means the act or process of altering something in some way. This word may be used to describe anything from hemming your pants to editing a manuscript.