The Great Vowel Shift explained

The Great Vowel Shift (GVS) was a major change in the pronunciation of English vowels that took place between 1350 and 1700. It is one of the features that clearly separates Middle English from Modern English.

Because English spelling was becoming standardised as the GVS was in progress, the GVS is partly responsible for many peculiarities in English spelling. It is the reason why the spelling of many English vowels doesn't match up with the equivalent vowels in neighbouring European languages.

The GVS didn't happen overnight; nor did it happen everywhere at the same time. It's not as if everyone in England woke up one morning, speaking in a completely different way to how they spoke the previous night. Instead, the GVS was a series of chain shifts that affected the Middle English long vowels. Although some short vowels have also changed in pronunciation since Middle English, these changes are not considered to be part of the GVS.

Dissecting the vowels – the mechanics of the GVS

Middle English had seven long vowels which were arranged like this. A word containing the vowel in question is given underneath the IPA symbol. Note that none of the words match up with their present day pronunciations:

i:                      u:

time             mouse

 e:                    o:

see               moon

  ɛ:                   ɔ:

 east             stone

            a:

        name


æi      ɑʊ

say   law


Listen to this clip here to get an idea of how these vowels were pronounced before the GVS began to take place. I’d definitely recommend it if you’re unfamiliar with IPA.

As my crudely-drawn diagram shows, the first change to occur was the breaking of the high vowels /i:/ and /u:/, starting somewhere between 1400-1500 AD. By about 1600, they were now pronounced [əi] and [əu] respectively (listen here). At the same time, or possibly a little later, [a:] moved forwards to [æ:]. To get an idea of what the shift from [a:] to [æ:] sounds like, think of someone from Northern England pronouncing cart, then imagine the same person saying cat, but holding the vowel for longer than usual. You should be able to tell that the vowel has moved further forwards in the mouth.

Now that a gap has been created where the high vowels /i:/ and /u:/ once were, the mid vowels /e:/ and /o:/ moved upwards to [i:] and [u:] respectively to fill the gap (stage 2 on the diagram). In effect, they have been pulled upwards. This stage was complete by about 1500. Soon after, /ɛ:/ and /ɔ:/ joined in the pull chain by shifting upwards to [e:] and [o:], filling the gap that was left behind (stage 4).

The /æ:/ in name and the /æi/ in day then moved upwards to [ɛ:] (stage 5) filling up the empty space left as a result of the previous stage of the chain shift. Although there is no low long vowel to take the place of /ɔ:/, another vowel sound shifts to fill the gap. The vowel in words such as law was once a diphthong [ɑʊ] (much the same as the vowel in out today). It was smoothed to [ɔ:] soon after original /ɔ:/ in stone was pulled upwards to [o:].

This is the first chain shift of the GVS completed, but the vowels aren’t done yet! A further chain shift took place from about 1600-1700. /e:/, which by this stage is found in words spelled with <ea> such as meat, moves up to [i:] (stage 6). This causes a merger between meat and meet. Once again, /ɛ:/ (now in words such as late) fills the gap that has been left behind, moving up to [e:].

The major chain shifts are now complete, but there are a few further changes still to go. The diphthongs /əi/ and /əu/ change to [ʌɪ] and [ɑʊ] in the 1700s, before changing to their modern pronunciations of [aɪ] and [aʊ] a little later.

Also, the long mid vowels [e:] and [o:] have become diphthongs in most dialects of English, including RP and General American. Name and stone are pronounced [eɪ] and [oʊ] or [əʊ], although they are still pronounced as long vowels in many American dialects and also in Yorkshire and Scotland.

Now let's look at the present day pronunciation of the Middle English long vowels and diphthongs to see how the pronunciation of these vowels has changed since the Great Vowel Shift:

 i:                                     u:
see, east                       moon

  eɪ                               oʊ, əʊ
 name, say                     stone

                                       ɔ:
                                     law

aɪ                                  aʊ
time                              mouse

Exceptions to the Great Vowel Shift

Although sound changes tend to be regular, not all words underwent certain phases of the GVS. For example, <ea> did not take the final step to [iː] in several words, such as great, break, steak, swear, and bear. The presence of [r] in swear and bear caused the vowel quality to be retained, but not in all cases. After all, bear no longer rhymes with fear, which did shift upwards. 

Other exceptions are father and rather, which failed to become [ɛː], and broad, which failed to become [oʊ]. The word room, which was spelled as roum in Middle English, retains its Middle English pronunciation, so it is an exception to the shifting of /uː/ to [aʊ]. This is because it is followed by /m/, a labial consonant. Another example is soup, whose movement to [aʊ] was blocked by the final /p/, also a labial consonant.

Shortening of long vowels at various stages produced further complications. <ea> is again a good example, shortening commonly before dental or alveolar consonants such as <t>, <d> and <th>. So we have words such as dead, head, threat, wealth, read (past tense) etc, which no longer rhyme with deal, heal, weak and reap. 

Soon after the GVS, <oo> was shortened from [uː] to [ʊ] in a few words such as blood and flood. When /ʊ/ moved forwards to [ʌ] in the South of England, these words were taken with it. Think of how the word cup is pronounced in the North of England compared to how it's pronounced in the South to get an idea of the difference between [ʊ] and [ʌ].

Some time later, probably in the early 1700's, many instances of /u:/ were shortened again to [ʊ], especially before /k/, /d/ and less commonly, /t/. As a result, book, foot and good do not rhyme with root, mood and goose even though the vowels were once identical.

Conclusion

Although this is a very brief article, I hope that you have come away knowing a little bit more about the fascinating series of sound changes known as the Great Vowel Shift.