Great Vowel Shift
Perhaps the biggest single change in English pronunciation happened during the transition from Middle English to Modern English. Linguists call this the Great Vowel Shift. The shift began c. 1300 and continued through c. 1700, with the majority of the change occurring in the 15th and 16th centuries. So the language of Chaucer is largely pre-shift and the language of Shakespeare is largely post-shift, although the changes were underway before Chaucer was born and continued on after Shakespeare had died.
During the Great Vowel Shift, English speakers changed the way they pronounced long vowels. Before the shift, English vowels were pronounced in much the same way that they are spoken in modern continental European languages. After the shift, they had achieved their modern phonological values.
For example, a Middle English speaker would pronounce the long e in sheep as we pronounce the word shape today. Fine was pronounced fien (as in fiend). Sea was pronounced like the modern say.
The difference can be seen in similar words that enter English before and after the shift. For example, the long i sound in polite, a word which makes its appearance c. 1450 from the Latin politus, meaning polished, burnished, cultivated underwent the shift. The similarly constructed police, which was borrowed a hundred years later from the Medieval Latin politia, missed the shift and is pronounced in the traditional, continental manner.
Okay, so what exactly changed in the shift? Basically it was a shift in the position of the tongue when the long vowels were pronounced. The shift didn’t affect short vowels, which we pronounce today much like Chaucer did. But with long vowels, the tongue moved up in the mouth and either further forward or back. If you pronounce the letters A and E several times in succession, you can feel your tongue moving forward and back in your mouth. A is a fronted vowel; it is pronounced with the tongue forward. E is a backed vowel, pronounced with the tongue back. After the shift, fronted vowels were pronounced with the tongue higher and further forward than previously and backed vowels were pronounced higher and further back. And the long i and long u sounds, which prior to the shift were already pronounced with the tongue high, became diphthongs—vowel sounds with two distinct elements.
Also, in some words the long vowels e and o shifted to become short vowels, especially in compounds. Hence, we have the difference in pronunciation between bone, from the Old English ban, and bonfire, which is literally a bone fire or funeral pyre. Scotland retained the original pronunciation longer, spelling it bane-fire until c. 1800. Similarly the long e in sheep shortened in the word shepherd.
Now the shift wasn’t completely consistent. Some words resisted the change. Sea shifted, but great and break didn’t. As a result ea has two distinct sounds in English.
The shift wasn’t consistent over different regions either. The shift occurred later and was weaker as you moved northward into the North of England and into Scotland. So Scottish pronunciation is closer to Chaucer’s than is the modern London accent.
Copyright 1997-2015, by David Wilton