The Processes of Sound Change

FROM THE LECTURE SERIES: The Story of Human Language

By John McWhorter, Ph.D., Columbia University

Humans rely on language to such an extent that we cannot practically conduct ourselves now if we are deprived of it. Today, about 6000 known languages exist. However, they were not always present. Languages keep evolving into newer languages, and given our dependence on the spoken tongue, a large amount of this change happens via changes in the sound. 

Latin inscription in concrete.
Over the course of many centuries, a number of languages have evolved from Latin.
(Image: Stefano Pellicciari/Shutterstock)

The sound of language, and the concept of language in general, is a very vast one, which is why languages can be found to be of various characteristics and unique attributes.

All the differences between various languages are testimony to the fact that language continues to gradually but continuously change. There are some languages that utilize ‘clicks’, called Khoi – San, which exist in certain parts of South – Western Africa. These clicks are not actually ornamental, they are similar to vowels and consonants, and are imperative to form a word and its meaning. 

Then there are languages in Australia which only workaround three verbs. Then there are languages, such as the Yupik Eskimo, which have words that encompass the meaning of entire English sentences.

Sound is of more importance in language than we realize. Out of about 6000 languages that we know of, only around 200 are practically written. The rest simply are passed on orally. Sound is, in fact, what allows the evolution of language. Writing creates a sense of what is construed as right, which creates a resistance to change and therefore immensely slows down the process of evolution of language over time. 

A lot of changes happen to sounds over time, which go on to shape the way we hear languages. There are various processes that are typically known to linguists by now, which tend to keep happening to languages as time goes by. 

Learn more about the History of Language.


One aspect of how language changes are called assimilation, which is the process by which two sounds that are close to each other begin to sound more like each other as time goes by. 

A common example of the phenomenon is the early Latin phrase ‘in possibilis’, which slowly evolved to become the more familiar ‘impossibilis’, which has evolved into the English ‘impossible’. This happened because m is closer to p in sound than n is because the former two letters create a sound that relies more on the lips. It can practically be said that one language has turned to another because of the laziness of the mouth!

Consonant Weakening

Another common process that has often been seen in the whirlwind of languages is Consonant Weakening. Consonants, over time, have a tendency to weaken and subsequently disappear. 

For instance, the Latin for ‘ripe’ is ‘maturus’, whose reflex we have as ‘mature’ in English. 

Latin has slowly given way to a series of other languages, the big five: French, Italian, Portuguese, Spanish, Romanian, then the lesser-known Provencal and Catalan, and some even lesser-known ones. 

Within the big five, a number of consonant weakenings happened from Latin. For Example,  the t in Latin’s ‘maturus’ weakened to a d in old Spanish. Upon scrutiny, one can easily see how a [d] is, in fact, a softer version of [t]. 

Today, in Castilian Spanish, there’s an even bigger transformation, from ‘maduro’, to ‘mathuro’, the use of the famous Spanish [th].

 In Old French the word that came about was ‘mathur’, omitting the s and o. thereafter, the [th] gradually disappeared, creating ‘maur’, after which the vowels coalesced, which created what exists today as just ‘mûr’.

If one was to look at the word  ‘mûr’ today without any records of Latin, this development would’ve been really hard to track. Yet, this is how language evolves naturally.

This is a transcript from the video series Story of Human Language. Watch it now, on The Great Courses Plus.

Vowel Weakening

It is not just consonants that weaken over time, however; vowels weaken, too, in a process that might be called vowel weakening. 

An example that portrays this phenomenon very clearly is the word ‘name’, spelled as n-a-m-e. Although as English speakers we are used to the almost silent e, this vowel was, of course, there for a reason.

There was a time when the word ‘name’ was pronounced as ‘NAH-meh’, which gradually weakened to ‘NAH-muh’, employing the indistinct kind of sound, called the schwa. Soon thereafter, this, too, was gone. The spelling of the word preserves the quaint old pronunciation of the word. 

Vowel Weakening displays a kind of laziness, which is beautifully called the principle of least effort. A natural successor to the concept of consonant and vowel weakening is the notion of language disappearing. Why do languages not devolve into nothingness over time? A part of the answer to this question lies in another way that sounds change, which is that apart from weakening, vowels also have a tendency of shifting around.

Learn more about Language Death.

The Great Vowel Shift

While the name makes the Great Vowel Shift sound like a momentous day when an event occurred, it was, in fact, a gradual process that started in the late 1300s. It transformed English vowels to something quite unlike the languages it was most close to. Interestingly, the spellings, even till today, are indicative of what the language was like before the shift happened. 

While this is an extremely brief, and really, incomplete explanation, the gist of the shift is that it happened based on the sounds of vowels, from the way they were before to the way they are now. These sounds are created from the way the vowels are formed in the mouth, which is the process that underwent a change during the Great Vowel Shift. 

Thus, words today which seem to have peculiar spellings according to their pronunciations, such as food, which should ideally have been spelled as fud, are spelled the way that they are because that is how they were pronounced in the past. 

The shift of vowels thus aids in protecting languages from moving towards obsolescence, by shifting to more comfortable positions, instead of simply disappearing. 

However, vowels and consonants are not the only processes that lead to changes in sound. Over time, tones, which are integral elements of many languages, also go through changes. 

Changes in Tones

Tones are of tantamount importance in a number of languages, such as Cantonese, in which there are at least six different tones.
These changes in tones, however, are not really how languages begin. Imagine a small word, with different endings. It is natural for each different ending to render a different tone to the word. Over time, the endings got dropped off, creating words that got their distinction from tones. 

Even though the proliferation of writing has, to a large extent, reduced the speed of transformation in language, it is accurate to say that sounds continue to change in every language. They do not act as disruptions for the language, but as a bridge towards new languages. 

Learn More About How Language Changes.

Commonly Asked Questions about Sound Changes

Q: What is assimilation?

Assimilation is the process of sound change by which two sounds that are close to each other begin to sound like each other.

Q: What was the Great Vowel Shift?

The Great Vowel Shift began in the late 1300s, and caused a significant upward movement of vowels, creating a huge sound change and influencing the way we speak today.

Q: How does Vowel Weakening work?

During the process of sound change, vowels sometimes get softened in speech, and sometimes disappear from speech completely, resulting in changes in the language.

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